InTENSity Twin Stim III TENS & EMS Combo Unit – DI3717

InTENSity™ Twin Stim III Digital TENS + EMS Stimulator

The InTENSity Twin Stim III, model DI3717, is a portable, dual-channel device that combines transcutaneous electrical nerve stimulation and electrical muscle stimulation.

TENS programming provides sensory-level electrical stimulation for clinician-directed pain-management applications. EMS—also commonly called NMES—stimulates motor nerves to produce a visible or palpable muscle contraction for prescribed muscle-rehabilitation programs.

Unlike devices built primarily around body-part presets, the Twin Stim III gives the practitioner direct control over frequency, pulse width, intensity, treatment time, and mode-specific settings. Its four TENS programs and three EMS programs allow the device to support both pain-focused stimulation and structured contraction-and-relaxation programs.

The unit can operate from a replaceable 9V battery for portability or from the included AC wall adapter. It comes with two lead wires, four reusable 2" × 2" electrodes, a battery, an AC adapter, an operating manual, and a carrying case. 

Treatment mode, settings, electrode placement, and duration should follow the prescription and current operating manual. 

Product highlights

• Combination TENS and EMS/NMES stimulator

• Compass Health/Richmar item DI3717

• Prescription Class II medical device

• Two isolated output channels

• Supports one or two electrode-pair arrangements

• Four adjustable TENS programs

• Three programmable EMS modes

• Output adjustable from 0–105 mA per channel at 1,000 ohms

• Pulse frequency adjustable from 1–150 Hz

• Pulse width adjustable from 50–300 microseconds

• TENS Burst rate adjustable from 0.5 to 5 Hz

• EMS contraction time adjustable from 1–60 seconds

• EMS relaxation time adjustable from 0–60 seconds

• EMS ramp adjustable from 1–6 seconds

• Treatment timer adjustable from 1–60 minutes or continuous

• Independent intensity adjustment for each channel

• Automatic control lock after 30 seconds

• Open-circuit electrode detection

• Replaceable 9V battery operation

• Included AC wall adapter

• Removable belt clip

• Compact digital LCD interface

• Four reusable 2" × 2" electrodes included

• Carrying case included

• One-year manufacturer warranty

The ranges above are documented in the current sell sheet and Revision C manual. The manual specifies a ±5% tolerance for settings and ±10% tolerance for output intensity.

Quick specifications

TENS programs explained

The Twin Stim III includes four TENS programs. The current manual gives these clearer names than the generic “Mod 1” and “Mod 2” terminology used in some marketing material.

The Burst program uses a fixed 100 Hz pulse frequency within each burst while allowing the overall burst rate to be adjusted from 0.5–5 Hz. The other programs permit frequency adjustment from 1 to 150 Hz. 

Recommended customer-facing wording

Avoid assigning each mode to a specific diagnosis or claiming that one mode is always best for either acute or chronic pain. A safer presentation is the following:

• Normal: steady stimulation

• Burst: rhythmic groups of pulses

• Pulse Width Modulation: automatically varies pulse duration

• Pulse Rate Modulation: automatically varies pulse frequency

Mode, intensity, frequency, pulse width, and treatment time should follow the practitioner’s directions.

EMS modes explained

Synchronous mode

Both channels stimulate at the same time and follow the same contraction, ramp, and relaxation cycle. This can support prescribed bilateral or paired-muscle applications where both electrode pairs should activate together.

Alternate mode

Channel 1 completes its stimulation cycle before Channel 2 begins. The manual requires the programmed OFF time to be at least as long as the complete ON cycle, including contraction and ramp periods.

Delay mode

Channel 2 begins after Channel 1 has already started, based on an adjustable delay. This creates overlapping but offset muscle-stimulation cycles rather than completely simultaneous or alternating output.

Contraction time is adjustable from 1–60 seconds, relaxation from 0–60 seconds, and ramp from 1–6 seconds. The manual defines the complete ON time as contraction plus ramp-up and ramp-down. 

Supported indications

What comes with the Twin Stim III?

Battery power vs. AC power

Safety lock and electrode detection

Automatic control lock

The front-panel controls lock approximately 30 seconds after the user stops changing the program or intensity. This helps prevent unintended setting or intensity changes.

To unlock the controls, press either channel’s intensity-down button. 

Electrode and open-circuit detection

When output is at or above 12 mA and the unit detects an open circuit—such as a loose lead, disconnected electrode, or pad that is not making proper contact—the affected amplitude resets to 0 mA. 

This feature can help identify the following:

• A disconnected electrode

• A loose 2 mm pin connection

• A lead wire not fully inserted

• A damaged cable

• A pad that has lifted from the skin

• Dry or worn hydrogel

It does not replace visual inspection of the electrodes, wires, skin, and connections.

Basic setup workflow

These steps summarize the operating manual and should not replace the prescription or complete instructions.

1. Review the prescribed settings. Confirm TENS or EMS, program, frequency, pulse width, intensity, treatment time, and any EMS ramp or work/rest parameters.

2. Install the 9V battery or connect the AC adapter. Follow the polarity and power instructions in the manual.

3. Connect the lead wires. Insert each device-side plug fully into the selected channel.

4. Connect the electrodes. Insert each 2 mm pin completely into the electrode socket so no conductive metal remains exposed.

5. Prepare the skin. Apply electrodes only to clean, dry, intact skin. Clip excessive hair when necessary; the manual says not to shave the stimulation site.

6. Place each complete electrode pair. One active channel requires two electrodes.

7. Turn on the device and select TENS or EMS.

8. Program the prescribed parameters before increasing intensity.

9. Raise each channel gradually. TENS is generally used at a strong but comfortable sensory level. EMS is commonly adjusted to obtain the practitioner-directed muscle response.

10. Turn the output down before repositioning or disconnecting anything.

11. After treatment, turn the unit off and return reusable pads to their liners.

Applying pads from the center outward, avoiding stretched adhesive, supporting excess lead-wire length, and removing pads in the direction of hair growth. 

Replacement electrodes and lead wires

The Twin Stim III uses standard pin-style electrode connections. Balego offers several appropriate accessory categories:

• 45-Inch TENS/NMES Replacement Lead Wires

• Balego TENS/NMES/FES Electrodes

• Electrotherapy Electrodes

• TENS Electrode Guides

Before substituting pads, confirm:

Read TENS/NMES Electrode Connectors: Pigtail vs. Tab for additional connector guidance.

Product comparison

Twin Stim III vs. other Balego electrotherapy devices

The Twin Stim IV is a rechargeable two-modality device with 18 TENS and 18 NMES programs, the Select Combo II is a rechargeable four-modality unit, the Balego EMS Digital is a dedicated dual-channel NMES device, and the Twin Stim Plus is a four-channel system with TENS, EMS, IFC, and Russian stimulation.

Twin Stim III vs. Twin Stim IV

The Twin Stim III is not automatically inferior because it is an earlier generation. It may be preferable when a practitioner wants direct access to frequency, pulse width, ramp, contraction, relaxation, and delay settings without navigating numerous body-area programs.

The Twin Stim IV may be preferable when rechargeable power, body-part presets, custom U1 programs, and compliance tracking are priorities.

Choose the Twin Stim III when:

• Both TENS and EMS are required.

• Direct manual programming is preferred.

• A replaceable 9V battery is useful.

• AC wall power is needed for stationary use.

• Synchronous, alternate, and delay EMS patterns fit the prescription.

• A strong adjustable output range is required.

• Body-part presets and IFC or Russian stimulation are unnecessary.

Choose the Twin Stim IV when you prefer:

• Rechargeable operation is preferred.

• Preset body-area programs simplify setup.

• Numerous TENS and NMES programs are desired.

• Compliance records are useful.

• The user prefers a guided interface over traditional manual programming.

Choose the Select Combo II when you need:

• IFC and Russian stimulation are needed in addition to TENS and NMES.

• Rechargeable operation is preferred.

• Two channels provide enough electrode coverage.

• Preset and customizable programs are both important.

Choose the four-channel unit when:

• More than two independent electrode pairs are needed.

• Large or multiple treatment regions must be covered.

• TENS, EMS, IFC, and Russian modes are all required.

• Two independent treatment timers are useful.

Troubleshooting guide

Important safety information

Rx Only. Use the InTENSity Twin Stim III only as directed by a licensed practitioner and according to the current instruction manual. Do not use it with a demand-type cardiac pacemaker or implanted defibrillator. Do not apply stimulation through the head, over the front or sides of the neck, over cancerous lesions, or over swollen, infected, inflamed, irritated, or poorly innervated areas. Pregnancy safety has not been established. Consult the prescribing practitioner regarding epilepsy, heart disease, circulation disorders, impaired sensation, recent surgery, or unexplained pain. Stop treatment if stimulation causes persistent pain, burning, skin irritation, or another unexpected reaction.

Frequently asked questions

Is the InTENSity Twin Stim III a TENS unit or an EMS unit?

It is both. The Twin Stim III combines four TENS programs for prescribed pain-management applications with three EMS programs for clinician-directed muscle stimulation. 

Is a prescription required?

Yes. Compass Health identifies DI3717 as a Class II Rx device, and both the manual and public device record state that it is restricted to prescription use. 

What is the maximum output?

The manufacturer specifies an adjustable maximum of 105 mA per channel into a 1,000-ohm load, with adjustments in 1 mA steps. Actual delivered current depends on the connected load and product tolerances. 

How many TENS modes are included?

Four:

• Burst

• Normal

• Pulse Width Modulation

• Pulse Rate Modulation

The display labels are B, N, M, and M1.

How many EMS modes are included?

Three:

• Synchronous

• Alternate, also called Asynchronous in some marketing material

• Delay

Is EMS the same as NMES?

In portable electrotherapy product descriptions, EMS and NMES are often used for the same general category of stimulation: electrical pulses intended to activate motor nerves and produce muscle contraction. For a fuller comparison, read TENS vs. NMES: Differences, Uses, and Device Guide.

What frequency range does the Twin Stim III provide?

The general TENS and EMS pulse-frequency range is 1–150 Hz. Burst mode uses an adjustable burst rate of 0.5–5 Hz with a fixed 100 Hz frequency inside the burst. 

What is the pulse-width range?

Pulse width is adjustable from 50–300 microseconds in 10-microsecond increments. 

What is the treatment-timer range?

The timer is adjustable from 1–60 minutes in one-minute steps or may be set to continuous operation. Timed sessions count down and stop automatically; continuous sessions must be stopped manually. 

Can the unit run from a wall outlet?

Yes. DI3717 includes an AC wall adapter and can also operate from a 9V alkaline battery. 

Is the Twin Stim III rechargeable?

No integrated rechargeable battery is identified. Its standard portable power source is a replaceable 9V battery.

How many electrodes can be used?

One active channel uses one complete electrode pair. With both channels active, the unit can operate four electrodes.

What electrodes come with the unit?

The manual lists four EP2020WC2-INTM reusable white-cloth electrodes measuring 2" × 2". 

What replacement lead wires fit?

Compass Health lists WW3005 45-inch standard lead wires as approved for the Twin Stim III. Balego offers them as 45-inch TENS/NMES replacement lead wires.

Why did the controls suddenly stop responding?

The safety lock activates after approximately 30 seconds without a setting or intensity adjustment. Press either channel’s intensity-down button to unlock the controls. 

Why did the intensity return to zero?

The open-circuit safety system may have detected a loose wire, disconnected pad, lifting electrode, or another break in the circuit. At output levels of 12 mA or higher, the unit resets amplitude to zero when an open circuit is detected. 

Does the Twin Stim III have a compliance meter?

A treatment history or compliance record feature is not described in the Revision C manual reviewed. Do not add one to the page. The newer Twin Stim IV does include treatment-use tracking.

Is Twin Stim III the same as Twin Stim Plus III?

No. The Twin Stim III DI3717 is a two-channel TENS and EMS device. The Four-Channel Twin Stim Plus 3rd Edition is a different product with four channels and TENS, EMS, IFC, and Russian stimulation.

Does the manufacturer list HCPCS codes?

E0730 for the TENS unit and A4595 for electrotherapy supplies. Coding does not guarantee insurance eligibility or payment; coverage and documentation requirements must be confirmed with the payer.

Additional Recommended Resources

• TENS vs. NMES: Differences, Uses and Device Guide

• TENS/NMES Electrode Connector Guide

• TENS Unit Guides and Mode Education

• NMES Protocols, Settings and Electrode Placement

• Contact Balego