BTL-199

K250309 · BTL Industries, Inc. · QPL · Aug 7, 2025 · Neurology

Device Facts

• Record ID: K250309
• Device Name: BTL-199
• Applicant: BTL Industries, Inc.
• Product Code: QPL · Neurology
• Decision Date: Aug 7, 2025
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 882.5890
• Device Class: Class 2
• Attributes: Therapeutic

Intended Use

The BTL-199 is intended to stimulate peripheral nerves for relief of chronic intractable pain, post-traumatic pain, post-surgical pain and/or for relief of chronic painful diabetic peripheral neuropathy in the lower extremities. The BTL-199 is for use on patients 18 and older.

Device Story

BTL-199 is an electromagnetic stimulator for non-invasive peripheral nerve stimulation to provide pain relief. System comprises a main console with color touch screen and three specialized applicators (AP-C-1, AP-C-2, AP-C-4/5) for various body areas. Device delivers focused electromagnetic pulses; operator selects preset protocols or customizes parameters (frequency up to 150 Hz, time up to 30 minutes, intensity 0-100%). Used in hospitals and clinics by medical professionals. Safety features include a patient-held therapy discomfort button, coil temperature monitoring (max 43°C), and an intensity predictor function to prevent overheating. Output allows physicians to manage chronic pain conditions; clinical benefit derived from nerve depolarization via time-varying magnetic fields.

Clinical Evidence

No clinical data provided. Substantial equivalence is supported by bench testing, including electrical safety (IEC 60601-1), electromagnetic compatibility (IEC 60601-1-2), software lifecycle (IEC 62304), risk management (ISO 14971), and biocompatibility (ISO 10993-1, -5, -10). Performance testing validated temperature sensor accuracy and intensity predictor function.

Technological Characteristics

Electromagnetic stimulator; system console (generator, computer, control panel) and applicators. Materials: Aluminum alloy, ABS, PC, Stainless steel, PE. Energy: Electromagnetic pulses (biphasic waveform). Connectivity: Standalone. Sterilization: Non-sterile. Software: Microprocessor-controlled with touch screen interface. Safety: Temperature sensor (max 43°C), intensity predictor function.

Indications for Use

Indicated for patients 18+ with chronic intractable pain, post-traumatic pain, post-surgical pain, or chronic painful diabetic peripheral neuropathy in lower extremities.

Regulatory Classification

Identification

A transcutaneous electrical nerve stimulator for pain relief is a device used to apply an electrical current to electrodes on a patient's skin to treat pain.

Predicate Devices

• Axon Therapy (K233364)
• MagVenture Pain Therapy (K230014)

Submission Summary (Full Text)

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FDA U.S. FOOD & DRUG ADMINISTRATION

August 7, 2025

BTL Industries, Inc.
David Chmel
CEO North America
362 Elm Street
Marlborough, Massachusetts 01752

Re: K250309
Trade/Device Name: BTL-199
Regulation Number: 21 CFR 882.5890
Regulation Name: Transcutaneous Electrical Nerve Stimulator For Pain Relief
Regulatory Class: Class II
Product Code: QPL
Dated: January 28, 2025
Received: February 3, 2025

Dear David Chmel:

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 (the 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 available 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.

Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device"

U.S. Food & Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993
www.fda.gov

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K250309 - David Chmel
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(https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90, Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review, the QS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

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 (reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reporting-combination-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 Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 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-devices/medical-device-safety/medical-device-reporting-mdr-how-report-medical-device-problems.

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medical-devices/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-devices/device-advice-comprehensive-regulatory-assistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email ([e-mail]) or phone [phone] or 301-796-7100).

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K250309 - David Chmel
Page 3

Sincerely,

Amber T. Ballard -S

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 Quality
Center for Devices and Radiological Health

Enclosure

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FORM FDA 3881 (8/23)
Page 1 of 1
PSC Publishing Services [phone]
EF

| DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration Indications for Use | Form Approved: OMB No. 0910-0120 Expiration Date: 07/31/2026 See PRA Statement below. |
| --- | --- |
| 510(k) Number (if known) K250309 | |
| Device Name BTL-199 | |
| Indications for Use (Describe) The BTL-199 is intended to stimulate peripheral nerves for relief of chronic intractable pain, post-traumatic pain, post-surgical pain and/or for relief of chronic painful diabetic peripheral neuropathy in the lower extremities. The BTL-199 is for use on patients 18 and older. | |
| Type of Use (Select one or both, as applicable) ☑ Prescription Use (Part 21 CFR 801 Subpart D) ☐ Over-The-Counter Use (21 CFR 801 Subpart C) | |
| CONTINUE ON A SEPARATE PAGE IF NEEDED. | |
| This section applies only to requirements of the Paperwork Reduction Act of 1995. *DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.* | |
| The burden time for this collection of information is estimated to average 79 hours per response, including the time to review instructions, search existing data sources, gather and maintain the data needed and complete and review the collection of information. Send comments regarding this burden estimate or any other aspect of this information collection, including suggestions for reducing this burden, to: Department of Health and Human Services Food and Drug Administration Office of Chief Information Officer Paperwork Reduction Act (PRA) Staff [e-mail] | |
| "An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB number." | |

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# 510(k) Summary K250309

## General Information

Sponsor: BTL Industries, Inc.
362 Elm Street
Marlborough, MA 01752
Tel: [phone]
Fax: [phone]

Applicant: BTL Industries, Inc.
362 Elm Street
Marlborough, MA 01752
Tel: [phone]
Fax: [phone]

Contact Person: David Chmel
BTL Industries, Inc.
[e-mail]

Summary Preparation
Date: 6 August 2025

## Device Name

Trade/Proprietary Name: BTL-199
Primary Classification Name: Electromagnetic Stimulator, Pain Relief
Classification Regulation: 882.5890, Class II
Classification Product Code: QPL

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# Legally Marketed Predicate Device

The BTL-199 is a state-of-the-art electromagnetic energy device with accessories and is substantially equivalent to the current product that is already cleared for distribution in the USA under the following 510(k) Premarket Notification numbers:

Predicate device #1:
Device name: Axon Therapy
Original 510(k) Sponsor: NeuraLace Medical Inc.
510(k) Number: K233364

Predicate device #2:
Device name: MagVenture Pain Therapy
Original 510(k) Sponsor: Tonica Elektronik A/S
510(k) Number: K230014

# Product Description

The BTL-199 is an electromagnetic stimulator that delivers brief, focused electromagnetic pulses to non-invasively stimulate peripheral nerves, providing pain relief.

The device consists of a main unit and specialized applicators, designed to deliver precise and effective therapy. The main unit is equipped with an intuitive color touch screen that provides step-by-step guidance for the operator throughout the therapy process. The device features a preset treatment protocol for ease of use, while also allowing operators to customize parameters to meet specific therapeutic needs. Adjustable parameters include frequency (up to 150 Hz), therapy time (up to 30 minutes), and intensity (0-100%). The interface displays detailed information about the therapy settings and session progress (i.e., treatment duration). The device uses a temperature sensor to monitor the temperature of the coil to ensure that the maximum permissible temperature of the applicator's contact areas (i.e., 43°C) are not exceeded. It also has an intensity predictor function that limits the maximum adjustable intensity of the device based on the therapy parameters set, so as not to overheat and damage the device.

The device is equipped with three sets of applicators: AP-C-1, AP-C-2, and AP-C-4/5. Each applicator is intended for a different body area depending on the size and shape of the treated body part.

- Applicator AP-C-1 is intended for treatment of larger body areas, such as back, waist, thighs, etc.
- Applicator AP-C-2 is intended for treatment of smaller body areas, such as hands, arms, legs, etc.
- Applicators AP-C-4/5 (AP-C-4 and AP-C-5 - for each side of the body respectively) is primarily intended for treatment of waist and lower back.

# Indications for Use

The BTL-199 is intended to stimulate peripheral nerves for relief of chronic intractable pain, post-traumatic pain, post-surgical pain and/or for relief of chronic painful diabetic peripheral neuropathy in the lower extremities. The BTL-199 is for use on patients 18 and older.

# Non-clinical Testing (Performance, Bench Testing)

The BTL-199 device has been thoroughly evaluated for electrical safety. The device has been found to comply with the following applicable medical device safety standards:

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IEC 60601-1 Medical electrical equipment – Part 1: General requirements for basic safety and essential performance
IEC 60601-1-2 Medical electrical equipment – Part 1-2: General requirements for basic safety and essential performance - Collateral standard: Electromagnetic compatibility – Requirements and tests
IEC 62304 Medical device software – Software life cycle processes
ISO 14971 Medical devices – Application of risk management to medical devices
ISO 10993-1 Biological evaluation of medical devices – Part 1: Evaluation and testing within a risk management process
ISO 10993-5 Biological evaluation of medical devices – Part 5: Tests for in vitro cytotoxicity
ISO 10993-10 Biological evaluation of medical devices – Part 10: Tests for irritation and skin sensitization

Temperature testing at the applicator surface was also provided to ensure it remained within safe non-therapeutic levels, in addition to validation testing for the temperature sensor and intensity predicator function.

## Clinical Testing

Not applicable

## Technological Characteristics

The BTL-199 device has the same intended use and comparable technological characteristics and principles of operation to its predicate devices. The BTL-199 device and its predicates are comprised of a system console and applicator(s). The system console consists of the generators, computer, and the control panel.

The mechanism of action and technological similarities and differences between the BTL-199 device and the predicate devices are described below in the comparison table. The differences do not raise any new safety or effectiveness questions.

## Substantial Equivalence

The subject device has the same intended use and comparable technological characteristics and principles of operation to its predicate devices. Therefore, the subject device is substantially equivalent to the predicate device.

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Comparison with the Predicate Devices

| 510(k) number Device name Company name | K250309 BTL-199 BTL Industries, Inc. | K233364 Axon Therapy NeuraLace Medical Inc. | K230014 MagVenture Pain Therapy Tonica Elektronik A/S | |
| --- | --- | --- | --- | --- |
| | Subject device | Predicate device | Predicate device | |
| Regulation | 21 CFR 882.5890 Transcutaneous electrical nerve stimulator for pain relief. | 21 CFR 882.5890 Transcutaneous electrical nerve stimulator for pain relief. | 21 CFR 882.5890 Transcutaneous electrical nerve stimulator for pain relief. | None |
| Product code(s) | QPL | QPL IPF | QPL | None |
| Indications for use | The BTL-199 is intended to stimulate peripheral nerves for relief of chronic intractable pain, post-traumatic pain, post-surgical pain and/or for relief of chronic painful diabetic peripheral neuropathy in the lower extremities. The BTL-199 is for use on patients 18 and older. | The Axon Therapy is intended to stimulate peripheral nerves for relief of chronic intractable pain, post-traumatic pain, post-surgical pain and/or for relief of chronic painful diabetic peripheral neuropathy in the lower extremities. The Axon Therapy is for use on patients 18 and older. | The MagVenture Pain Therapy is intended to stimulate peripheral nerves for relief of chronic intractable, post traumatic and post-surgical pain for patients 18 years or older. | None |
| Therapy protocol | Therapy intensity: Individually estimated Therapy time: 800 s Therapy frequency: 0.5 Hz Number of pulses: 400 | Therapy intensity: Individually estimated Therapy time: 800 s Therapy frequency: 0.5 Hz Number of pulses: 400 | Therapy intensity: Individually estimated Therapy time: 800 s Therapy frequency: 0.5 Hz Number of pulses: 400 | None |

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| Treatment areas | Any area, such as hand, arm, waist, buttock, thigh, calf, back and lower back etc. | Any area, such as hand, arm, chest, waist, buttock, thigh, calf, back and low back etc. | Any area, such as hand, arm, waist, buttock, thigh, calf, back and lower back etc. | None |
| --- | --- | --- | --- | --- |
| Treatment facilities | Hospitals & Clinics | Hospitals & Clinics | Hospitals & Clinics | None |
| Basic technology | Electromagnetic stimulation | Electromagnetic stimulation | Electromagnetic stimulation | None |
| Pulse frequency | 0.5 Hz per protocol
Up to 150 Hz
• AP-C-1 (150 Hz)
• AP-C-2 (50 Hz)
• AP-C-4/5 (150 Hz) | 0.5 Hz per protocol
Up to 2 Hz | 0.5 Hz per protocol
Up to 100 Hz | Not significantly different |
| Maximum repetition rate | Up to 150 pps
• AP-C-1 (150 pps)
• AP-C-2 (50 pps)
• AP-C-4/5 (150 pps) | Up to 2 pps | Up to 100 pps | Not significantly different compared to K230014 predicate device. |
| Pulse amplitude | 0-100% | 0 to 100%
A maximum of 80% intensity is recommended to reduce the risk of coil overheating | 0-100% | None |
| Therapy time | 13 min per protocol
(800 seconds)
Up to 30 minutes | 13 min per protocol
(800 seconds) | 13 min per protocol
(800 seconds) | Not significantly different |
| On-Cycle Duty Period | 800 s per protocol | 800 s per protocol | 800 s per protocol | None |

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| | Device Therapy/On time period is up to 30 minutes | Device Therapy/On time period is up to 800 seconds | Device Therapy/On time period is up to 800 seconds | |
| --- | --- | --- | --- | --- |
| Off-duty rest period | N/A | N/A | N/A | None |
| Pulse mode | Standard | Standard | Standard | None |
| Pulse width (±20 %) | Biphasic (190-280 μsec)
• AP-C-1 (280 μsec)
• AP-C-2 (190 μsec)
• AP-C-4/5 (260 μsec) | Biphasic (290 μsec) | Biphasic (280-320 μsec) | Not significantly different |
| Maximum output power | 100% at up to 14 pps
• AP-C-1 (13 Hz)
• AP-C-2 (14 Hz)
• AP-C-4/5 (8 Hz) | 100% at 2 pps | 100% at up to 15 pps | Not significantly different compared to K230014 predicate device |
| Waveform | Biphasic | Biphasic | Biphasic, Halfsine, Biphasic Burst, Monophasic | None |
| Maximum surface temperature | Below 43°C (on applicator surface) | 45°C or 41°C for total of 9 minutes (on coil surface) | 43°C (or 48°C for <10 minutes) | None |
| Peak Magnetic Field at coil surface (T) | Up to 2.0 T
• AP-C-1 (0.5 to 1.8 T)
• AP-C-2 (0.7 to 2.0 T)
• AP-C-4/5 (0.35 to 1.3 T) | Not publicly available | Up to 2.6 T | Not significantly different |

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| Peak Magnetic Field Gradient dB/dt in coil center at 20mm distance from the applicator surface | Up to 16 kT/s
• AP-C-1 (10 kT/s)
• AP-C-2 (16 kT/s)
• AP-C-4/5 (11 kT/s) | Not publicly available | Up to 26 kT/s | Not significantly different |
| --- | --- | --- | --- | --- |
| Applied parts and applied parts areas | AP-C-1 (14.6 cm)
AP-C-2 (13.6 cm)
AP-C-4/5 (29.3 cm) | Coil 60BF-NL
16 cm | Butterfly coils: 150 mm
Circular coils:110-126 mm
Special coils: 160×80 mm
(MMC-140-II, MCF-140, RT-120-II, MMC-90, MCF-125, Cool-B65, Cool-125) | None
Both devices were tested in accordance with ISO 10993 series |
| Timer | Yes | Not publicly available | Not publicly available | Not significantly different |
| Software/Firmware/Microprocessor control | Yes | Yes | Yes | None |
| Indication Functions | On/Off Status
Ready Status | On/off status
Ready status | Not publicly available | None |
| Power source | 100 – 240 V AC,
50–60 Hz | 100 – 240 V AC,
50–60 Hz | 120V AC,
50/60 Hz | None |
| Power consumption | 3000 W | Power consumption: 800VA
Maximum, 115W idle | Maximum 2700VA | Not significantly different |
| User Interface | Touch screen | LED display | LED display | Not significantly different |

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| Housing Material Construction | Main unit – Aluminium alloy, ABS, PC, Stainless steel
Applicator - PC-ABS, PE | Stimulator: AL sheet EN AW 5754 H111
Coil: ABS | Stimulator: Aluminum, Aluzinc
Coils: PVC, ABS, PA, POM | Not significantly different |
| --- | --- | --- | --- | --- |
| Coil construction and parameters | Single copper coil with air core. | Butterfly copper coil with air core. | Butterfly, Single or Special coils with copper winding and air core. | Not significantly different |
| Weight & Dimensions | Stimulator: 70 kg
Including packaging and accessories: 91 kg
Applicators:
AP-C-1 – 2.7 kg
AP-C-2 – 2.3 kg
AP-C-4/5 – 2 kg
Unit with cart: 23 x 39 x 29 in (592 x 985 x 730 mm) | Stimulator: 17 kg
Coil: 3.2 kg
Full system (with cart): 54 kg
Unit: 485 x 380 x 165 mm | Not publicly available
Stimulator: 210 x 530 x 400 mm
33 kg/35 kg | Not significantly different |
| Sterilization | Non-sterile when used | Non-sterile when used | Non-sterile when used | None |

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# Substantial Equivalence Discussion

## Therapy Time

The therapeutic protocol cleared for the predicate device specifies a treatment time of 13 minutes; however, each patient is unique and requires an individualized approach. Since this device is intended for use by medical professionals as an Rx-only device, it allows therapy durations of up to 30 minutes. We believe that treatment length should be determined by the physician based on each patient's condition, and therefore offer this option. Additionally, the default time settings for the cleared therapy protocol are the same as those for the predicate device: 800 seconds.

In case of use therapy parameters that would be outside the recommended parameters stated above, the device has several built-in functions which should help to avoid any undesirable effects - e.g. a therapy discomfort button, which must be available to the patient at all times during therapy and which can be used to interrupt the therapy in case of any discomfort (its use should prevent any overstimulation, pain or any discomfort sensation or thermal damage to the patient). There is also a temperature sensor that constantly monitors the temperature of the coil to ensure that the maximum permissible temperature of the applicator's contact areas are not exceeded (its use should prevent thermal damages to the patient). The device also has an intensity predictor function that limits the maximum adjustable intensity of the device based on the therapy parameters set, so as not to overheat and damage the device. The Operator's manual also urges the operator to regularly monitor the patient's feedback and never leave the patient alone during therapy.

For the reasons outlined above, this difference does not introduce any new or modified risks or concerns related to safety or effectiveness and the subject device is equivalent to the selected predicate.

## Maximum Repetition Rate / Pulse Frequency

The subject device's maximum pulse repetition rate of 150 pps exceeds the predicate device's 2 pps; however, subject device's maximum pulse repetition rate is very similar to K230014. Moreover, the subject device is intended for prescription use only (Rx-only), meaning it must always be prescribed by a physician, who is responsible for the final settings of therapy parameters for each individual patient and as mentioned above, the subject device allows physicians to set the same preset protocol as its predicate.

From the effectiveness and design point of view, the subject device is comparable to the K233364 predicate device - since the subject device allows the use of a therapeutic protocol with the same parameters that were cleared for the K233364 predicate device and these therapeutic parameters for achieving the indications for use are also described in the operator's manual.

- Therapy intensity: Individually estimated
- Therapy time: 800 s
- Therapy frequency: 0.5 Hz
- Number of pulses: 400

The operator's manual clearly states that treatment parameters (e.g., repetition rate, pulses per train, number of trains, number of pulses, inter train interval, treatment time)

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not included in the list above have not been evaluated for effectiveness in the relief of chronic intractable pain, post-traumatic pain, post-surgical pain and/or for relief of chronic painful diabetic peripheral neuropathy in the lower extremities.

For the reasons outlined above, the subject device is comparable to predicate devices, and this difference does not introduce any new or modified risks or concerns related to safety or effectiveness.

## Maximum Output Power

The subject device's maximum output power is very similar to K230014. The maximum output power of the subject device is 100% at frequencies up to 14 Hz, compared to the K233364 predicate device, which maintains 100% output up to 2 Hz. However, at the therapeutic protocol frequency of 0.5 Hz, both devices are capable of maintaining a maximum output of 100% intensity throughout the entire 800 s therapy duration. At 2 pps the subject device and the K233364 device are both able to obtain a maximum output of 100% signifying they are equally effective. This demonstrates that both devices are comparably effective. The difference in maximum output power does not raise new or different questions of safety and effectiveness.

## Magnetic Coil Construction

The subject device applicators use a single, circular-coil design, whereas the K233364 predicate device employs a figure-of-eight (double) coil. The K230014 predicate uses both circular and butterfly coils. Both coil types are similarly constructed - copper windings encapsulated in a plastic housing, and operate on the same basic principle: a time-varying magnetic field induces an electric field in tissue that depolarizes nerve axons. Circular coils offer the practical advantage of unrestricted orientation, however, both geometries achieve the same intended peripheral-nerve-stimulation effect.

The differences in spatial distribution of the magnetic field, and its parameters such as maximum surface flux density (T) or field gradient (dB/dt) between circular and double coils are negligible in practice and have not been shown to affect safety or efficacy. Therefore, this difference does not introduce any new or modified risks or concerns related to safety or effectiveness.

## Conclusion

Based upon the intended use and the known technical data provided in this pre-market notification, the BTL-199 device has been shown to be substantially equivalent to the currently marketed predicate devices.