Sonic Technology Digital Neuro Stim Pocket Tens is a is portable, battery operated TENS (Transcutaneous Electrical Nerve Stimulator) used for the symptomatic relief and management of chronic (long term) pain. Relieve Pain and Rebuild, Re-educate, Tone, and Stimulate Muscles. TENS is a non evasive method intended to be used to alleviate pain. The Sonic TENS sends impulses through the skin that stimulate the nerve (or nerves) in the treatment area. Features include: Dual Channels which may be isolated between channels - meaning you can either station. Wave Form: Modified, square wave form with zero net direct current (DC) component. Pulse Amplitude: 0 to 80 mA each channel, adjustable (500 ohm load). Pulse Frequency: 2-150 Hz adjustable. Pulse Width: 60 - 250 Microseconds adjustable. Modulation mode: Pulse width is automatically varied in a cyclic pattern over an interval of nominally 4.0 seconds. Burst Mode 7 Pulses per Burst, 2 Bursts per second. 100 Hz internal frequency of burst. Maximum Charge: 20 micro coulombs per pulse. Power Source: 9 Volt Alkaline Battery. Battery Life: 70 hours average usage (alkaline). Size 3.5 " x .5 x 2.5". Weight of unit without battery: 3 oz. Since 1981 Sonic Technology has guaranteed all of our products. If you have any problem, please contact us for an immediate replacement.