Catalog edition · October 15, 2026How everyday comfort gadgets work · Sleep · Massage · Feet · Supplements · Direct-sale checks
Advanced Biology Post
Part MW-03Massage & WarmthTENS unitFDA 510(k) K182120

Omron Max Power Relief TENS Unit, Model PM500 (formerly PM3032)

A handheld, battery-powered unit that sends short electrical pulses between two self-adhesive pads on the skin. This entry reads the manual, the FDA record and the Amazon listing to explain the modes, the timer, the pads and who should not use it.

Advanced Biology Post Editorial Team

Exploded view

Part MW-03 · callouts from the Omron manual · Oct 15, 2026
Omron Max Power Relief TENS unit in black with its display showing the mode names, beside two white Long Life electrode pads on their cord
  1. 1DisplayLCD that shows the selected mode, the intensity level (1 to 15), the minutes left, a pad icon if a pad comes loose and a low-battery icon.
  2. 2Intensity buttonUp and down arrows that step the output through 15 levels, one level per press.
  3. 3MODE and ON/OFF buttonsMODE steps through the nine preset pulse patterns, restarting at the lowest intensity each time; ON/OFF starts and stops the session.
  4. 4Electrode cordOne cord that plugs into the bottom of the unit and splits into two snap connectors, one per pad: the unit has a single output channel.
  5. 5Long Life PadsTwo reusable gel pads, 2.5 x 4 in each; current leaves through one pad and returns through the other, so the manual says both must be on the skin.
Parts named as in Omron’s PM500 instruction manual (“Know your unit” and “Features”), read Oct 15, 2026. The photo is the Amazon listing’s main image with the printed retail box removed.

Spec plate

PM500 (REF HV-F023-Z) · from the manual and FDA record · Oct 15, 2026
Model
Max Power Relief PM500; Omron says this SKU replaced PM3032
Dimensions
2 x 4.4 x 1 in (52 x 112 x 25 mm)
Weight
About 3.5 oz (100 g) with batteries
Power
3 V DC from 2 x AAA batteries (included)
Output
Single channel; about 1 to 238 Hz; pulse duration 150 µs; up to 70 V into a 500 Ω load
Pads
2 Long Life Pads, 2.5 x 4 in; up to 150 uses per pair
Timer
Stops automatically after 15 minutes
Care
Pads rinsed under slow cold water with fingertips, no soap; unit wiped with a damp cloth
Warranty
1 year on the unit; 30 days on the pads
Regulatory status
FDA 510(k) K182120, Jan 10, 2019; Class II, 21 CFR 882.5890; over-the-counter
Modes and intensity
9 preset modes (Tap, Knead, Rub, Arm, Lower Back, Leg, Foot, Joint, Shoulder) × 15 intensity levels

Sources: Omron’s PM500 manual and product page [1][2], the K182120 510(k) summary [3] and FDA’s device identifier database [4], read Oct 15, 2026. The Amazon listing disagrees with itself: its technical table still says model PM3032, while its bullets, “manufacturer part number” and in-box photo say PM500. Omron’s page states the product “has been updated to a new SKU (old – PM3032, new – PM500)”.

01Operating principle

The unit turns two AAA batteries into a train of very short electrical pulses and sends them across the skin between two pads, in patterns and strengths you pick.

  1. Batteries become pulses

    A microprocessor drives a regulated-current output. Each pulse lasts 150 microseconds, the rate runs from about 1 to 238 pulses per second depending on the mode, and the peak is 70 V into a 500-ohm test load [1][3].

  2. Two pads close the circuit

    Current flows out through one pad, through the skin and tissue beneath, and back through the other. That is why the manual says the device “won’t work with just one pad”, and why it asks for the pads to sit on either side of the area, at least 1 inch (3 cm) apart and never overlapping [1].

  3. A mode is a pattern

    Each of the nine modes is a preset sequence of pulse rates. The manual describes the Foot mode as a series of low-rate tapping and pulsing sensations and the Rub mode as high-rate pulsing; only one mode runs at a time [1].

  4. Intensity, then the timer

    You start at level 1 and step up until the sensation is clear but comfortable. The session ends on its own after 15 minutes; Omron’s stated limit is 30 minutes per session, up to three times a day [1].

  5. It notices a loose pad

    If a pad lifts off, the pad icon appears; the 510(k) summary lists an automatic no-load trip and automatic shut-off among the safety features [3].

02Fit check

Good fit

  • Adults who want a pocket-size unit with fixed presets, including one labeled Foot, and three buttons instead of an app
  • People who prefer AAA batteries to a charger; Omron estimates about four months per set at 15 minutes a day
  • Anyone who wants a device with a public FDA 510(k) record they can read for themselves

Poor fit

  • Anyone who wants two channels or four pads at once: this unit has one channel and one pair of pads
  • Use in the bath or shower, while sleeping or while driving, all of which the manual rules out
  • Buyers who want the option to return it: the Amazon listing is non-returnable

Check first

  • The manual and the FDA record say not to use it with a cardiac pacemaker, implanted defibrillator or other implanted metallic or electronic device
  • The manual lists pregnant women among the people who should not use it, and asks anyone with a known heart or seizure condition to follow their physician’s precautions
  • Pads must not go on the head, face, mouth, neck or throat, near the heart, across the chest, or on the genital area, and the manual warns against pads on the soles of both feet, or on both calves, at the same time
  • Not on open wounds, rashes, swollen, red or inflamed skin, or skin that lacks normal feeling; ask a clinician first after recent surgery

03What the FDA record and the research say

Which FDA record applies depends on the model letter. Omron’s PM500 is listed in FDA’s device identifier database (GUDID) under premarket submission K182120 [4]. In that 510(k), cleared Jan 10, 2019, the device is named “Maxpower Relief Model PM3032B”, and the summary says it is identical to the original PM3032 (K141978, cleared Dec 3, 2014) “except the CPU and related components”, with the same modes, waveforms, dimensions and pads [3][5]. Put plainly: the unit on the Amazon listing on Oct 15, 2026 is the PM500, its FDA record is K182120, and electrically it is the same design as the PM3032.

In neutral terms, the 510(k) clears it for over-the-counter use by adults on sore or aching muscles of the lower back, arms, legs, shoulder or foot after strain from exercise or normal household work activities; K182120 also added a second product code with a further use tied to the Shoulder mode [3]. A 510(k) means FDA found the device substantially equivalent to one already on the market; it is not a finding about how well it works for any one person (see our guide to FDA wording).

On effect, the evidence is thin. A 2019 Cochrane overview drew its data from eight Cochrane reviews covering 51 randomized trials and 2,895 adult participants with pain lasting more than three months; the evidence in every review was rated very low quality, mostly from small trials, and the authors could not conclude with any confidence whether TENS helps or harms [7]. Omron’s own manual adds that “the long-term effects of electrical stimulation are unknown” and that TENS devices do not cure disease or injuries [1].

Before you buy

The Amazon listing says “This item is non-returnable” (a refund or replacement only if it arrives damaged or defective). Check the implanted-device and pregnancy warnings above before ordering, not after.

04Setup and care

This is how Omron’s manual says to set up, run and store the unit; it is not a promise of any result.

  1. Batteries and cord

    Open the battery cover on the back with a coin, insert two AAA cells by the polarity marks, and close it. Plug the electrode cord into the jack at the bottom and snap one connector onto each pad.

  2. Pads on, then power on

    Peel the clear film, press the pads onto clean, dry, unbroken skin at least 1 inch apart, and only then press ON/OFF. Lotions, creams or sprays under the pads are ruled out; on hairy skin the pads may not stick.

  3. Mode and intensity

    Press MODE until the mode you want shows, then raise intensity one step at a time from level 1. Do not move the pads while the unit is on; turn it off first.

  4. Stop and store

    The unit stops after 15 minutes. Remove the pads, stick them on the plastic holder with the cords attached, and keep everything in the pouch away from heat and sunlight.

  5. Clean and replace pads

    After about 15 uses, rinse the sticky side under slow cold running water with your fingertips for a few seconds and let it air-dry. Replace the pair when it no longer sticks or more than a quarter of a pad stays off the skin; Omron rates a pair at up to 150 uses.

05Price and where it is sold

On Oct 15, 2026 the Amazon listing showed $49.80, shipped and sold by Amazon.com, in stock, with the return line “This item is non-returnable, but if the item arrives damaged or defective, you may request a refund or replacement.” Omron’s own page listed an MSRP of $79.99 the same day [2]. Replacement Long Life Pads are sold separately. See the listing on Amazon (as an Amazon Associate we earn from qualifying purchases).

06Who should look elsewhere

  • Anyone with a pacemaker, implanted defibrillator or any other implanted metallic or electronic device (contraindication in the manual and the FDA summary).
  • Anyone who is pregnant, and children: the manual says the device has not been evaluated for pediatric use.
  • Anyone who would rather avoid electrical pulses on the skin: the RENPHO foot massager works with kneading, air and warmth instead.
  • Anyone who needs two channels, a rechargeable battery or a returnable listing.

Sources

  1. Omron Healthcare. Max Power Relief PM500 instruction manual (contraindication, warnings, modes, specifications, warranty). Accessed Oct 15, 2026. link
  2. Omron Healthcare. Max Power Relief TENS Unit PM500, product page (SKU change note, specifications, MSRP). Accessed Oct 15, 2026. link
  3. U.S. Food and Drug Administration. 510(k) K182120, Omron Healthcare Maxpower Relief Model PM3032B: record and 510(k) summary. Decision Jan 10, 2019. record · summary PDF
  4. U.S. Food and Drug Administration. Global Unique Device Identification Database entry for Omron PM500 (device identifier 00073796635008), via openFDA. Accessed Oct 15, 2026. link
  5. U.S. Food and Drug Administration. 510(k) K141978, Omron MAXPOWER RELIEF Model PM3032. Decision Dec 3, 2014. link
  6. Electronic Code of Federal Regulations. 21 CFR 882.5890, the classification regulation for TENS devices (Class II). link
  7. Cochrane Database of Systematic Reviews. Overview of Cochrane reviews of TENS in adults with long-lasting pain (CD011890.pub3), 2019. PMID 30941745. link

This entry is educational and is not medical advice. It describes what a device does and what its labeling says; it does not say the device will change any health condition. Ask a qualified clinician before using a device like this if you are pregnant, have an implanted device, have reduced feeling in the area, or have an existing condition.