The Quad-Stim is a combination Transcutaneous Electrical Nerve Stimulation (TENS) and Electrical Muscle Stimulation (EMS) digital device used for pain relief, relaxation, and stimulating muscles. The device has four controllable and independent output channels, each of which can be connected to an electrode pair. The battery operated device has a swing-door panel of individually controlled pulse amplitude intensity levels, ranging from 1 to 100. The device has adjustable pulse rate and width, 5 TENS modes, 3 EMS modes, 2 adjustable timers, 24 preset programs, and storage for up to 60 sets of operation records. Now available as an Over-The-Counter device! Package Includes :8 Reusable Electrode PadsLead Wires4 AA BatteriesUser Manual & Electrode Placement GuideCarrying CasePulse Amplitude : Adjustable, 0-100 mA peak into 500 ohm loadWave Form : Asymmetrical Bi-Phasic Square PulseSize : 13.8cm(L) x 7.8cm(W) x 2.8cm(H)Output Type : TENS and EMS Timer : Two Adjustable timers, 1-60 minutes or ContinueRamp Time : Adjustable, 1~8 seconds, 1 Sec./Step On Time : Adjustable, 2~90 seconds, 1 Sec./Step Off Time : Adjustable, 0~90 seconds, 1 Sec./Step Compliance Meter : 60 sets of individual operation records Pulse Rate : Adjustable, from 2 to 150 Hz, 1Hz/Step Pulse Width : Adjustable, from 50 to 300μs, 10μs/step and Adjustable, from 50 to 400 microseconds, 10μs/step Weight : 276 grams and 425 grams Modes : B, N, M, SD1, SD2(TENS) & C, S, A(EMS) and B, N, M, SD1, SD2(TENS) & C, S, A(EMS) and 24 Preset Programs under P Mode and B, N, M, SD1, SD2(TENS) & C, S, A(EMS) and 37 Preset Programs under P Mode Power Supply : 4 x AA Batteries or Lithium Battery.