The MStim Drop LGT-233 is intended to provide ankle dorsiflexion in individuals who have a dropped foot as a consequence of upper motor neuron injury. The device electrically stimulates muscles in the affected leg to provide ankle dorsiflexion of the foot and/or knee flexion or extension; thus, it also may improve the individual's gait. The MStim Drop LGT-233 may also:

·Prevent/retard disuse atrophy

· Maintain or increase joint range of motion

•Increase local blood flow

Device Description

The MStim Drop LGT 233 is a wearable foot drop device, which is mainly consist s of stimulator main unit, electrode lead wire, electrodes pad, leg bandage and battery charger. The stimulator main unit can be charge by the battery charger.

The device can control the out stimulation and treatment time setting by APP application provided by the manufacturer, and it can trigger and control the pulse stimulation on and off by detecting the swing phase of gait during walking. The device was design to use FES (Functional Electrical Stimulation) to treat and improve the patient s foot drop and help to improve walking ability. It has two modes: Training mode, Walk mode. Training mode is suitable for muscle training when the patient is seated or lying down (patient lacking active training), which can promote muscle recover, prevent muscle atrophy, improve joint range of motion, and increase local blood flow. Walk mode is walking with the electrical stimulation.

AI/ML Overview

The MStim Drop Model: LGT-233 is an external functional neuromuscular stimulator intended to provide ankle dorsiflexion in individuals with dropped foot due to upper motor neuron injury. It electrically stimulates muscles to improve gait and may also prevent/retard disuse atrophy, maintain or increase joint range of motion, and increase local blood flow.

Here's an analysis of the provided information regarding acceptance criteria and studies:

1. Table of Acceptance Criteria and Reported Device Performance

The provided document (a 510(k) summary) does not explicitly state "acceptance criteria" in a quantitative, measurable sense for clinical performance. Instead, it demonstrates substantial equivalence to predicate devices through a comparison of technical specifications and an assertion of compliance with various electrical safety and biocompatibility standards. The reported device performance is largely a direct comparison of its technical specifications to those of the predicate devices.

Here's a table summarizing the comparison of key technical elements. "SE" in the remark column indicates "Substantially Equivalent” as claimed by the manufacturer. "Minor difference" remarks are explained in the "Comparison in Detail(s)" section of the document.

Elements of Comparison	Subject Device (MStim Drop Model: LGT-233)	Predicate Device I (L300 Go System, K162407)	Predicate Device II (MyGait Stimulation System, K141812)	Remark
Indications for Use	Provides ankle dorsiflexion, improves gait, prevents atrophy, maintains/increases ROM, increases local blood flow.	Provides ankle dorsiflexion, assists knee flexion/extension, improves gait.	Provides ankle dorsiflexion and knee flexion/extension, improves gait, prevents/retards atrophy, facilitates muscle reeducation, maintains/improves ROM, promotes local blood circulation.	SE
Apply parts	Leg	Leg and foot	Leg and foot	SE
Power Sources	Adapter supply: AC 100~240V, Battery: 3.7V, 1200mAh, lithium.	Battery operated	Battery operated	Minor difference (Note 1)
Indicator display	LED and APP	--	--	Minor difference (Note 1)
Method of Line Current Isolation	Battery operated	--	Medical Class II Power Adapter	SE
Number of Modes for Micro current stimulation	2 (Training mode, Walk mode)	Two modes: Biphasic Symmetric and Biphasic Asymmetric.	2	SE
Number of Channels for Micro current stimulation	1	1-2 channels depending on cuff.	2	SE
Synchronous or Alternating	Not applicable – single channel device	Alternating	Synchronous or alternating	SE
Regulated Current or Regulated Voltage	Regulated Voltage	Current	Regulated Current	SE (Note 2 refers to Timer Range, not this)
Software/Firmware/Microprocessor control	Yes	Yes	Yes	SE
Automatic Overload Trip	Yes	Yes	Yes	SE
Automatic No-load Trip	Yes	Yes	Yes	SE
Automatic Shut Off	Yes	Yes	No	SE
Patient Override Control	Yes	Yes	Yes (ON/OFF Button)	SE
Indicator Display (Status, Low Battery, Voltage/Current Level)	Yes (On/Off Status, Low Battery); No (Voltage/Current Level)	Yes for all	Yes for all	SE (Remark for each, although Voltage/Current is 'No' for subject device)
Timer Range	1min-60min, stepping 1min	Max stimulation duration (clinician selectable) Training mode: 5-60 minutes	5 to 120min in steps of 5 min	Minor difference (Note 2)
Console weight	60g (main unit)	Control Unit: 60g, EPG: 60g, Lower leg FSC:150g, Thigh cuff: 300g, Foot Sensor: 25g	78g	SE
Housing Materials and Construction	ABS	Mixed (Polycarbonate + ABS, Biocompatible fabric, POM Hi, TPU)	ABS	SE
Waveform	Biphasic square	Biphasic Symmetrical	Biphasic	SE
Shape	Rectangular	Rectangular	Rectangular	SE
Maximum Output Voltage (+/- 10%)	50V @ 500Ω, 90V @ 1KΩ, 120V @ 2KΩ, 130V @ 10KΩ	Lower leg: 50V@500Ω, 130V@2KΩ, 130V@10KΩ; Thigh: 50V@500Ω, 130V@2KΩ, 130V@10KΩ	45V @ 500Ω, 90V @ 1KΩ, 120V@2KΩ, n/a @10KΩ	Minor difference (Note 3)
Maximum output Current	100mA @ 500Ω, 90mA @ 1KΩ, 60mA @ 2KΩ, 13mA @ 10KΩ	Lower leg: 100mA@500Ω, 65mA@2KΩ, 13mA@10KΩ; Thigh: 100mA@500Ω, 65mA@2KΩ, 13mA@10KΩ	90mA @ 500Ω, 90mA @ 1KΩ, 60mA@2KΩ, n/a @10KΩ	Minor difference (Note 3)
Frequency range	10~80Hz	10, 15, 20, 25, 30, 35, 40, 45 Hz	10 to 80Hz in 1Hz steps	Minor difference (Note 4)
Pulse width range	50~500µs	100, 150, 200, 250, 300µs (each: positive and phase)	Symmetrical: 50 ~~400µs in steps of 50µs; Asymmetrical: pos.: 50 ~ 400µs, Neg.: 200~~1600µs	Minor difference (Note 4)
Pulse duration	50~500µs	Positive phase: 100, 150, 200, 250, 300 µs; Negative phase: 100, 150, 200, 250, 300 µs	Symmetrical: 50 ~~400µs in steps of 50µs; Asymmetrical: pos.: 50 ~ 400µs, Neg.: 200~~1600µs	Minor difference (Note 4)
Net Charge	0uC @ 500Ω	0µC using inverted balanced phases	0µC @ 500Ω Balanced pulses	SE
Maximum Current Density	Train mode: 0.532mA/cm²@500Ω, Walk mode: 0.53mA/cm²@500Ω	Lower leg (small cuff): 1.63 mA/cm² (rms), Lower leg (regular cuff): 1.04 mA/cm² (rms), Thigh: 0.23 mA/cm² (rms)	1.51 mA/cm² @500Ω	Minor difference (Note 5)
Maximum Power Density	Train mode: 5.66 mW/cm²@500Ω, Walk mode: 5.62 mW/cm²@500Ω	Lower leg (small cuff): 13.4 mW/cm², Lower leg (regular cuff): 8.5 mW/cm², Thigh: 1.9 mW/cm²	0.024 W/cm²	Minor difference (Note 5)
ON time	For Train mode: 2~40s, For Walk mode: N/A	Training mode: 4-20 sec, Gait mode: 1-10 sec	1 to 4 sec in 0.1sec steps	Minor difference (Note 6)
OFF time	For Train mode: 2.0~60.0s, For Walk mode: N/A (swing phase detecting)	Training mode: 4-20 sec, Gait mode: not limited (swing phase detecting)	1 to 30 sec in 1sec steps	Minor difference (Note 6)
Contraction and Relaxation time	Adjustable	--	Adjustable	SE
Environment for operating	Temperature: 5 to 40°C; Rel. humidity: ≤80%	--	No specific values listed in comparison table.	SE
Environment for storage and transport	Temperature: -20 to 55°C; Rel. humidity: ≤93%	--	No specific values listed in comparison table.	SE
Biocompatibility	Compliant with ISO10993-5, -10, -12	No specific standards listed in comparison table.	No specific standards listed in comparison table.	SE
Electrical Safety, EMC	Compliant with IEC 60601-1, -2-10, -1-2, -1-11, IEC 62133-2	IEC 60601-1, IEC 60601-1-2, IEC 60601-2-10, FCC part 15 subpart C and B1	IEC 60601-1:2005+A1:2012; IEC 60601-1-11:2010; IEC 60601-2-10:2012; IEC 60601-1-2:2007	SE

2. Sample size used for the test set and the data provenance (e.g., country of origin of the data, retrospective or prospective)

The document primarily relies on bench testing for safety and performance evaluation against recognized standards (IEC, ANSI, ISO). There is no mention of a human clinical study or "test set" in the context of clinical performance data used for this 510(k) submission. Therefore, sample size and data provenance for a clinical test set are not applicable here.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g., radiologist with 10 years of experience)

Not applicable, as no clinical test set for performance involving ground truth established by experts is described for this submission. The submission focuses on substantial equivalence based on technical specifications and compliance with safety standards.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set

Not applicable, as no clinical test set requiring adjudication is described.

5. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

Not applicable. This device is an electrical stimulator, not an AI-powered diagnostic tool requiring reader performance evaluation.

6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done

Not applicable. This is not an algorithm-only device.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)

For the safety and performance evaluation reported, the "ground truth" used is compliance with various international standards for medical electrical equipment (e.g., IEC 60601 series), battery safety (IEC 62133-2), and biological evaluation (ISO 10993 series). These standards define acceptable limits and testing methodologies for device characteristics. No clinical outcomes data or expert consensus on clinical effectiveness is presented as "ground truth" in this submission.

8. The sample size for the training set

Not applicable. This device does not appear to incorporate machine learning algorithms that require a "training set" in the context of AI model development.

9. How the ground truth for the training set was established

Not applicable, as no training set for AI model development is mentioned.

Summary

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Image /page/0/Picture/0 description: The image shows the logo of the U.S. Food and Drug Administration (FDA). On the left is the Department of Health & Human Services logo. To the right of that is the FDA logo, which is a blue square with the letters "FDA" in white. To the right of the blue square is the text "U.S. FOOD & DRUG ADMINISTRATION" in blue.

November 5, 2021

Guangzhou Longest Science & Technology CO., Ltd. % Jet Li Regulation Manager Guangzhou Keda Biological Tech Co., Ltd. 6F, No. I TianTai road, Science City, LuoGang District Guangzhou, Guangdong 510060 China

Re: K202110

Trade/Device Name: MStim Drop Model: LGT-233 Regulation Number: 21 CFR 882.5810 Regulation Name: External Functional Neuromuscular Stimulator Regulatory Class: Class II Product Code: GZI, IPF Dated: October 5, 2021 Received: October 6, 2021

Dear Jet Li:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database located at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

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Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely.

Amber Ballard, PhD Assistant Director DHT5B: Division of Neuromodulation and Physical Medicine Devices OHT5: Office of Neurological and Physical Medicine Devices Office of Product Evaluation and Ouality Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known) K202110

Device Name MStim Drop Model: LGT-233

Indications for Use (Describe)

·Prevent/retard disuse atrophy

· Maintain or increase joint range of motion

•Increase local blood flow

Type of Use (Select one or both, as applicable)
-------------------------------------------------

X Prescription Use (Part 21 CFR 801 Subpart D)

| Over-The-Counter Use (21 CFR 801 Subpart C)

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510(k) Summary 510K number: K202110

This summary of 510(K) safety and effectiveness information is being submitted in accordance with the requirement of 21 CFR 807.92.

Date of the summary prepared: November 04, 2021 1.

Submitter'sInformation 2.

Company Name: Guangzhou Longest Science & Technology CO., Ltd. Address: 5&6F, Building B4, No.11, Kaiyuan Avenue, Science City, Guangzhou Hi-tech Industrial Development Zone, 510530 Guangzhou, Guangdong Province, P.R. China Phone: +86 020 6635 3999 Fax:+86 020 6635 3920 URL: www.longest.cn

E-mail: qzlongest@126.com

Contact Person: Xiaobing Luo (Deputy general manager) E-mail: service@longest.cn

Application Correspondent:

Company: Guangzhou KEDA Biological Tech Co., Ltd. Address: 6F, No.1 TianTai road, Science City, LuoGang District, GuangZhouCity, China

Contact Person: Mr. Jet Li

Tile: Regulation Manager

Tel: +86-18588874857

Email: med-jl@foxmail.com

3. Subject Device Information

Type of 510(k) submission: Traditional Common Name: External functional neuromuscular stimulator Trade Name: MStim Drop Model: LGT-233 Classification Name: Stimulator, neuromuscular, external functional; Stimulator, muscle, powered Review Panel: Neurology, Physical Medicine Product Code: GZI, IPF

Requlation Number: 882.5810, 890.5850

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Regulation Class: 2

Sponsor	Bioness Inc	Otto Bock HealthcareProducts GmbH
Device Name	L300 Go System	Otto Bock HealthcareProducts GmbH
510(k) Number	K162407	K141812
ProductCode	GZI, IPF	GZI; GZI
RegulationNumber	21 CFR §882.581021 CFR §890.5850	21 CFR 882.5850 and21 CFR 882.5810
RegulationClass	2	2

Predicate Device Information 4.

5. Device Description

6. Intended Use / Indicationsfor Use

The MStim Drop LGT-233 is intended to provide ankle dorsiflexion in individuals who have a dropped foot as a consequence of upper motor neuron injury. The device electrically stimulates muscles in the affected leg to provide ankle dorsiflexion of the flexion or extension; thus, it also may improve the individual's gait.

The MStim Drop LGT-233 may also:
Prevent/retard disuse atrophy
Maintain or increase joint range of motion

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· Increase local bloodflow

7. Test Summary

The Device has been evaluated the safety and performance by lab bench testing according to the following standards:

IEC 60601-1-2: 2014: Medical Electrical Equipment -Part 1-2: General requirements for basic salety 1. and essential performance. Collateral Standard: Electromagnetic Compatibility
IEC 60601-1:2005: Medical Electrical Equipment Part 1: General requirements for basic safety 2. and essential performance
1. IEC 60601-1-11: 2015: Medical Electrical Equipment - Part 1-11: General requirements for basic safety and essential performance. Collateral Standard: Requirements for medical electrical equipment and medical electrical systems used in the home healthcare environment
1. IEC 60601-2-10: 2012: A1 2016 Medical Electrical Equipment - Part 2: Particular requirements for the basic safety and essential performance of nerve and muscle stimulators.
1. ANSI IEEE C63.27-2017: American National Standard for Evaluation of Wireless Coexistence
1. IEC 62133-2: 2017: Secondary cells and batteries containing alkaline or other non-acid electrolytes-Safety requirements for portable sealed secondary cells, and for batteries made from them, for use in portable applications- Part 2: Lithium systems
1. Biological evaluation ofmedical device Part 10: Tests for irritation and skin sensitization(ISO 10993-10:2010)
1. Biological evaluation of medical device Part 5: Cytotoxicity test- In vitro method (ISO 10993-5:2009)

8. Comparison to predicate device and conclusion

The technological characteristics, features, specifications, mode of operation, and intended use of the MStim Drop Model: LGT-233 is substantially equivalent to the predicate devices quoted above. The differences between the subject device and predicate device do not raise new issues of safety or effectiveness.

Elements ofComparison	Subject Device	Predicate Device I	Predicate Device II	Remark
Device Nameand Model	MStim Drop Model: LGT-233	L300 Go System	MyGait StimulationSystem	--
Elements ofComparison	Subject Device	Predicate Device I	Predicate Device II	Remark
510 (K)Number	Applying	K162407	K141812	--
Product Code	GZI, IPF	GZI, IPF	GZI, IPF	--
RegulationNumber	882.5810, 890.5850	21 CFR § 882.581021 CFR § 890.5850	21 CFR 882.5810, 21 CFR § 890.5850	--
Indication foruse	The MStim Drop LGT-233 isintended to provide ankledorsiflexion in individuals whohave a dropped foot as aconsequence of upper motorneuron injury. The deviceelectrically stimulates musclesin the affected leg to provideankle dorsiflexion of the footand/or knee flexion orextension; thus, it also mayimprove the individual's gait.The MStim Drop LGT-233may also:Prevent/retard disuseatrophyMaintain or increase jointrange of motionIncrease local blood flow	The L300 Go System isintended to provide ankledorsiflexion in adult andpediatric individuals withfoot drop and/or assistknee flexion or extensionin adult individuals withmuscle w eakness relatedto upper motor neurondisease/injury (e.g.,stroke, damage topathways to the spinalcord). The L300 GoSystemelectricallystimulates muscles in theaffected leg to provideankle dorsiflexion of thefoot and/or knee flexion orextension; thus, it alsomay improve theindividual's gait.	The stimulation system isintended to provide ankledorsiflexion and knee flexionor extension in individuals withfoot drop and thigh muscleweakness following an uppermotor neuron injury ordisease.During gait, the stimulationsystem sends electric stimulito muscles in the affected leg,initiating dorsiflexion of the footand knee extension or flexionand may thus improve theindividual's gait. Thestimulation system may alsoprevent or retard atrophycaused by inactivity, facilitatemuscle reeducation, maintainor improve the range of motionin the joints and promote localblood circulation.	SE
Apply parts	Leg	Leg and foot	Leg and foot	SE
Power Sources	Adapter model: HYI11-005(USA) and HYI11-005(Europe)Adapter supply voltage: AC100~240V, 50/60HzAdapter output: DC 5V, 2ABattery: 3.7V, 1200mAh,lithium battery.	Battery operated	Battery operated	MinordifferenceNote 1
Indicatordisplay	LED and APP	--	--	MinordifferenceNote 1
Elements ofComparison	Subject Device	Predicate Device I	Predicate Device II	Remark
Method of LineCurrentIsolation	Battery operated	--	Medical Class II PowerAdapter	SE
Number ofModes forMicro currentstimulation	2(For Evaluation mode: nomicro current stimulation)	Two modes: BiphasicSymmetric and BiphasicAsymmetric.Applicable to both lowerleg and thigh position ofthe device.	2	SE
Number ofChannels forMicro currentstimulation	1	Lower leg small cuff- 1 channel;Lower leg regularcuff - 1 or 2 channels (in 2channel configuration,bothchannels function as asingle channel withseparately adjustablemedial / lateral stimulationintensity);Thigh cuff - 1 channel	2	SE
Synchronousor Alternating	Not applicable – singlechannel device	Alternating (at one timeonly one channel isactivated)	Synchronous or alternating	SE
RegulatedCurrent orRegulatedVoltage	Regulated Voltage	Current	Regulated Current	SENote 2
Elements ofComparison	Subject Device	Predicate Device I	Predicate Device II	Remark
Software/Firmware/Microprocessorcontrol	Yes	Yes	Yes	SE
Automatic OverloadTrip	Yes	Yes	Yes	SE
Automatic No-loadTrip	Yes.	Yes	Yes	SE
Automatic Shut Off	Yes.	Yes	No	SE
Patient OverrideControl	Yes	Yes	YesON/OFF Button	SE
IndicatorDisplay	On/OffStatus	Yes	Yes	Yes	SE
	LowBattery	Yes	Yes	Yes	SE
	Voltage/Curr entLevel	Yes	Yes	No	SE
Timer Range		Treatment time: 1min-60min, stepping 1min;Timer tolerance: ±2%;When finish, the devicecan stop output andprompt	Maxstimulationduration (clinicianselectable)Training mode: 5-60minutes	5 to 120min in steps of5 min	Minor differenceNote 2
Elements ofComparison	Subject Device	Predicate Device I	Predicate Device II	Remark
Console weight	60g (only main unit)	Control Unit: 60g, EPG:60g, Lower leg FSC:150g,Thigh cuff: 300g, FootSensor: 25g	78g	SE
HousingMaterials andConstruction	ABS	Remote Control:Bay State PolymerPA-2000RXEPG: Bay State PolymerPA-2000RX(Polycarbonate + ABS)Lower Leg FSC:Biocompatible fabric overplastic (POM Hi) skeletonThigh FSC: TPU FootSensor: ABS (Sensorhousing), Bay statePolymerPA-2000RX (Electronicshousing)	ABS	SE
Waveform	Biphasic square	Biphasic Symmetrical	Biphasic	SE
Shape	Rectangular	Rectangular	Rectangular	SE
MaximumOutput Voltage(+/- 10%)	50V ±10% @ 500Ω90V ±10% @ 1KΩ120V ±10% @ 2KΩ130V ±10% @ 10KΩ	Lower leg: 50V@500ΩThigh: 50V@500ΩLower leg: 130V@2K ΩThigh: 130V@2K Ωlower leg: 130V@10K ΩThigh: 130V@10K Ω	45V +-10% @ 500Ω90V +-10% @ 1KΩ120V +-10%@2K Ωn/a @10K Ω(no stimulation possible at10kΩ)	Minor differenceNote 3
Elements ofComparison	Subject Device	Predicate Device I	Predicate Device II	Remark
Maximumoutput Current	100mA ±10% @ 500Ω90mA ±10% @ 1KΩ60mA ±10% @ 2KΩ13mA ±10% @ 10KΩ	Lower leg: 100mA@500ΩThigh: 100mA@500ΩLower leg: 65mA@2KΩThigh: 65mA@2KΩLower leg: 13mA@10KΩThigh: 13mA@10KΩ	90mA (+/- 10%) @ 500Ω90mA (+/- 10%) @ 1KΩ60mA (+/- 10%)@ 2K Ωn/a @10K Ω(no stimulation possible at10KΩ)	Minor differenceNote 3
Frequencyrange	10~80Hz	10, 15, 20, 25, 30, 35, 40,45 Hz	10 to 80Hz in 1Hz steps	Minor differenceNote 4
Pulse widthrange	50~500µs;	100, 150, 200, 250, 300µs(each: positive and phase)	Symmetrical:50 ~~400µs in steps of50µsAsymmetrical:pos.: 50 ~ 400µs in stepsof 50µsNeg.: 200~~1600µs insteps of 100µs	Minor differenceNote 4
Pulse duration	50~500µs;	Positive phase:100, 150, 200, 250,300 µsNegative phase:100, 150, 200, 250,300 µs	Symmetrical:50 ~~400µs in steps of50µsAsymmetrical:pos.: 50 ~ 400µs in stepsof 50µsNeg.: 200~~1600µs insteps of 100µs	Minor differenceNote 4
Elements ofComparison	Subject Device	Predicate Device I	Predicate Device II	Remark
Net Charge	0uC @ 500Ω	0µC using invertedbalanced phases	0µC @ 500ΩBalanced pulses	SE
MaximumCurrentDensity	Train mode: 0.532mA/cm2@500Ω,Walk mode: 0.53mA/cm2@500Ω	Maximum current levelsare:Lower leg: 16.43 mA (rms)Thigh: 16.43 mA (rms)Maximum current densityis:Lower leg (small cuff):1.63 mA/cm2 (rms), forsmallest electrodes areaof 10.1 cm2Lower leg (regular cuff):1.04 mA/cm2 (rms), forsmallest electrodes areaof 15.8 cm2Thigh: 0.23 mA/cm2 (rms),for smallest electrodesareaof 72 cm2	1.51 mA/cm2 @500Ω,	Minor differenceNote 5
MaximumPower Density	Train mode: 5.66 mW/cm2@500Ω,Walk mode: 5.62 mW/cm2@500Ω	Lower leg (small cuff):13.4 mW/cm2, for smallestElectrodes area of 10.1 cm2Lower leg (regular cuff):8.5 mW/cm2, for smallestelectrodes area of 15.8 cm2Thigh: 1.9 mW/cm2,For smallest electrodesarea of 72 cm2	0.024 W/cm2	Minor differenceNote 5
ON time	For Train mode:2~40sFor Walk mode:N/A	Training mode: 4-20 secGait mode: 1-10 sec (themax stimulation durationafter triggering event isdetected)	1 to 4 sec in 0.1sec steps	Minor differenceNote 6
OFF time	For Train mode: 2.0~60.0sFor Walk mode: N/A(Asswing phase detecting)	Training mode: 4-20 secGait mode: not limited (Asswing phase detecting)	1 to 30 sec in 1sec steps	Minor differenceNote 6
Elements ofComparison	Subject Device	Predicate Device I	Predicate Device II	Remark
Contraction andRelaxation time	Adjustable, due todifferent modes.	--	Adjustable, due to different SEmodes.
Environment foroperating	Temperature: 5 to 40°C;Rel. humidity: ≤80%;	--		SE
Environmentfor storage andtransport	Temperature: -20 to 55°C;Rel. humidity: ≤93%;	--		SE
Biocompatibility	Electrode pad and Belt:Compliant withrequirements ofISO10993-5,ISO10993-10,ISO10993-12,standards	--		SE
Electrical Safety,EMC	Compliant withrequirements ofIEC 60601-1, IEC60601-2- 10 , IEC 60601-1-2,IEC 60601-1-11, IEC62133-2 safety standards	IEC 60601-1, IEC 60601-1-2, IEC 60601-2-10,FCC part 15 subpart Cand B1	IEC 60601-1:2005+A1:2012;IEC 60601-1-11:2010;IEC 60601-2-10:2012;IEC 60601-1-2:2007	SE

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Comparison in Detail(s):

Note 1 (Power Source(s) and Method of Line Current Isolation):

The power source is only energy source for the operation of the device, it do not affect the output of the micro current. And the device complies with IEC 60601-1 requirements for evaluation of safety. So such minor difference do not raise safety and effectiveness issue.

For display method, even there is minor difference on display design. However it is only for status and setting interface display, and the display APP function and interface had been evaluated in software

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validation; So such minor difference do not raise safety and effectiveness issue.

Note 2 (Timer Range ):

The design of the timer range is based on the intended use. For MStim Drop Model: LGT-233, the operating time is adjustable by operator according to physician direction. So the timer setting range difference would not impact its safety and effectiveness, comparing predicate devices.

Note 3 (Maximum Output Voltage and Maximum Output Current):

The effect of micro current stimulation is determined by micro-current output waleform and output current. There is only little difference between the output voltage and current of the subject device from the predicated devices, it can still obtain the same effect because our output voltage and output current are in the range which is similar to the value of K162407 and predicate device K 141812. Even the predicate device II have no stimulation at 10K ohm, but its output voltage at 500, 1K and 2 KOhm is similarto subject device; and the predicate device I have similar output voltage as proposed subject device,

Also, the subject device comply with IEC 60601-1, and IEC60601-2-10 for its safety verification, comparing with the predicate devices. Therefore, the minor difference would not affect safety and effectiveness of the subject.

Note 4 (Frequency and Pulse-width):

For Frequency: There is minor difference on frequency of output waveform pulse between subject device and predicate device I, but the frequency means that pulse number in a completed cycle of waveform, the frequency difference means that the pulse numbers difference which deliver to patient body per second. And the frequency of subject device is same to the one of predicate device II (K141812), so its minor difference would not impact the safety and effectiveness of subject device.

For Pulse width: The stimulation time of micro current stimulation is determined by pulse width of micro-current output waveform. Frequency and pulse is the time parameter of the waveform. There is only little difference between the pulse width of the subject device from the predicated device I, it can still obtain the same effect because output current and pulse width is similar to the value of Predicate device II (K141812). Also, the subject device complies with IEC 60601-1, and IEC60601-2- for safety evaluation. Therefore, the minor difference on pulse width would not affect its safety and effectiveness of subject device.

Note 5 (Maximum current density and Maximum power density):

The effect of micro current stimulation is determined by micro-current output pulse width and output current. Even there is only little difference between the value of current density and maximum power density of the subject device and the predicated device due to electrode pad size, but the value of current density and maximum power density of subject device are in the range which is similar to the value K162407. Even the maximum current density and the maximum power density of subject

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device is less than predicate device II (K141812), but its value was covered in predicate device l(K162407).

And the maximum power density meet with the maximum allowed value 0.25 (W/cm²) required in FDA guidance. Therefore, the subject device and predicate device are substantially equivalence on these parameters.

Note 6 (On time and OFF time):

On time and OFF time are designed according to the circuit design of the device for max stimulation time. Even there is minor difference for on time and Off time between subject device and predicate device. But for MStim Drop Model: LGT-233, the operating time is adjustable so that the operator can made applicable stimulation time to apply on patient body by adjusting operation time based on physician direction. So the minor difference for On time and Off time between subject device and predicate device would not affect safety and effectiveness of subject device.

Finial Conclusion:

The subject device MStim Drop Model: LGT-233 is Substantial Equivalence to the predicate devices.

Regulation Number and Section

§ 882.5810 External functional neuromuscular stimulator.

(a)
Identification. An external functional neuromuscular stimulator is an electrical stimulator that uses external electrodes for stimulating muscles in the leg and ankle of partially paralyzed patients (e.g., after stroke) to provide flexion of the foot and thus improve the patient's gait.(b)
Classification. Class II (performance standards).