iStim EV-906 Rechargeable 4-Channel TENS/EMS Unit—24-Pad Kit

The EV-906 is a rechargeable, four-channel electrotherapy device that combines TENS sensory stimulation and EMS muscle stimulation in one portable system.

Its four independently controlled output channels support up to four electrode pairs, or eight electrodes, during one treatment session. This gives the EV-906 greater placement flexibility than a standard dual-channel unit when a user needs bilateral stimulation, broader coverage, or multiple electrode-pair arrangements.

The EV-906 platform provides five adjustable TENS patterns and three adjustable EMS modes. Users can also control pulse rate, pulse width, intensity, treatment time, and—in EMS programming—ramp, contraction, and relaxation timing. The documented platform includes two treatment timers and a compliance meter that stores treatment-use records.

Includes 24 reusable electrodes in 2 × 2-inch and 2 × 4-inch sizes, four lead-wire sets, an instruction manual, and USB charging equipment.

• Rechargeable TENS and EMS combination device
• Four isolated output channels
• Up to eight electrodes connected at one time
• Independent intensity adjustment for each channel
• Five adjustable TENS modes
• Three adjustable EMS modes
• Pulse rate adjustable from 2–150 Hz
• Pulse width adjustable from 50–300 microseconds
• EMS ramp adjustable from 1–8 seconds
• EMS contraction time adjustable from 2–90 seconds
• EMS relaxation time adjustable from 0–90 seconds
• Separate treatment timers for Channels 1–2 and Channels 3–4
• Treatment time adjustable from 1–60 minutes or continuous operation
• Compliance meter storing up to 60 sessions and 999 total treatment hours
• Rechargeable lithium-battery configuration
• Four lead-wire sets
• 24 reusable electrodes
• FDA 510(k)-cleared over-the-counter TENS/EMS device
• One-year limited manufacturer warranty

The electrical specifications, modes, timers, and compliance-record capacity are documented in the EV-906 platform manual. The rechargeable configuration is covered by FDA clearance K201335.

Each EV-906 channel controls one lead wire and one pair of electrodes.

Four channels do not automatically produce a stronger treatment. The principal advantage is greater placement flexibility. Each channel’s intensity remains independently adjustable, allowing the output to be adapted to differences in electrode size, skin resistance, body location, and user tolerance. The EV-906 has four channels and supports up to eight electrodes.

TENS and EMS both use electrical pulses delivered through skin electrodes, but they are intended to create different responses.

Read TENS vs. NMES: Differences, Uses, and Device Selection for a more detailed explanation.

The EV-906 platform includes five manually adjustable TENS patterns.

Normal, Modulation, SD1, and SD2 permit adjustment of pulse rate and pulse width within the device’s available ranges. Burst mode uses a fixed 100 Hz internal pulse frequency with an adjustable burst rate from approximately 0.5–5 Hz.

For additional mode guidance, read What the Five TENS Modes Are Used For.

The EV-906 provides three EMS programming patterns.

In synchronous mode, the contraction time must be long enough to accommodate ramp-up and ramp-down. In alternate mode, the manual specifies that relaxation time should be at least as long as contraction time.

The EV-906 divides its four channels into two timer groups.

Each timer can be adjusted from 1–60 minutes or placed into continuous operation where permitted by the selected program. This allows the two channel groups to run for different lengths of time during the same modality session.

The dual timers do not mean that the device can operate TENS on one group and EMS on the other simultaneously. The selected modality applies across the session.

The EV-906 platform includes a compliance meter that can store:

• Up to 60 individual operation records
• Up to 999 total treatment hours

This feature may be useful for reviewing whether the device was operated and for approximately how long. It does not independently document electrode placement, clinical response, treatment quality, or whether the correct settings were selected.

The EV-906 is a rechargeable unit and includes USB charging equipment. FDA clearance K201335 specifically covers lithium-battery-powered EV-906 and EV-906A models.

The EV-906 is rechargeable, but it is not wireless. Four lead wires connect the device to the electrode pads.

Do not operate it while charging unless the instructions packaged with the current unit expressly permit use during charging.

1. Charge the unit

Charge the rechargeable battery using the supplied equipment before initial use.

2. Set all channel intensities to zero

Confirm that Channels 1–4 are at zero before connecting wires or applying electrodes.

3. Connect the lead wires

Insert one lead wire into each channel that will be used.

4. Connect the electrode pads

Attach two pads to each active lead wire before placing them on the skin.

5. Prepare the treatment area

Apply electrodes only to clean, dry, intact skin. Remove lotion, oil, perspiration, and dirt that could interfere with adhesion.

6. Position the electrodes

For TENS, pads are generally positioned around or near the intended treatment area.

For EMS, place them over the target muscle and appropriate motor-point region so that the intended muscle contracts.

7. Select TENS or EMS

Choose the modality that matches the intended goal.

8. Select the operating mode

Choose one of the five TENS modes or three EMS modes.

9. Adjust the parameters

Depending on the selected mode, set the following:

• Pulse rate
• Pulse width
• Ramp time
• Contraction time
• Relaxation time
• CH1–CH2 timer
• CH₃–CH₄ timer

10. Increase each channel separately

Raise one channel at a time until the desired TENS sensation or EMS contraction is reached.

11. Monitor the session

Reduce or stop the output for pain, burning, sharpness, uncontrolled movement, rapid fatigue, worsening symptoms, dizziness, or another unexpected reaction.

12. Turn all channels down before removal

Return all channel intensities to zero and turn off the device before removing or repositioning electrodes.

TENS commonly produces the following:

• Tingling
• Buzzing
• Tapping
• Rhythmic pulsing
• A changing sensation in modulation modes

The stimulation should be strong and clearly noticeable while remaining comfortable. Conventional sensory TENS generally should not create a forceful muscle contraction.

EMS begins with an electrical sensation and rises until the target muscle contracts.

A programmed EMS cycle may feel like

1. The stimulation rises gradually.
2. The muscle tightens.
3. The contraction is maintained.
4. The output gradually declines.
5. The muscle rests.
6. The sequence repeats.

The contraction should be controlled and tolerable—not sharp, burning, or painful.

Both are rechargeable four-channel TENS/EMS systems with large accessory packages. The clearest verified EV-805 distinction is its current 24-program listing and three included pad styles. The EV-906 platform has well-documented manual programming and compliance-record functions, with 30 programs.

The rechargeable EV-906 and EV-906A were cleared under FDA 510(k) K201335 for over-the-counter use.

The cleared TENS indication is temporary relief of pain associated with sore and aching muscles in the following:

• The low back
• The arms
• The legs

The labeling associates that discomfort with strain from exercise or normal household and work activities.

The cleared EMS indication is stimulation of healthy muscles to improve or facilitate muscle performance.

The product page should not state or imply that the EV-906:

• Cures chronic pain
• Treats arthritis itself
• Repairs injured muscles
• Reverses nerve damage
• Prevents blood clots
• Treats paralysis
• Replaces exercise or physical therapy
• Produces permanent pain relief

Do not use the EV-906 with a cardiac pacemaker, implanted defibrillator, or another implanted electronic device without specific medical and device-manufacturer guidance.

Do not apply stimulation:

• Across the chest
• Through the head
• Over the eyes or mouth
• On the front or sides of the neck
• Over the carotid sinus
• Over broken, infected, or significantly irritated skin
• Where an involuntary muscle contraction could create an injury
• In another location prohibited by the current manual

Obtain professional guidance before use in the presence of pregnancy, epilepsy, heart disease, recent surgery, impaired sensation, a bleeding tendency following trauma or fracture, or undiagnosed or changing pain.

Do not use the device while driving, operating machinery, bathing, swimming, or participating in an activity in which an unexpected contraction could be hazardous.

Replace a pad when it no longer adheres, develops curled edges, becomes dry or contaminated, produces concentrated stinging, or has a damaged connector.

The EV-906 Rechargeable 4-Channel TENS/EMS Unit is best suited to buyers who want the following:

• Four independent stimulation channels
• Up to eight electrodes in one setup
• Both TENS and EMS
• Detailed manual parameter adjustment
• Two treatment timers
• Compliance tracking
• Rechargeable battery power
• Four included lead wires
• A large 24-pad starter package