BioMedical Life Systems Micro Plus Microcurrent Electrical Nerve Stimulator is a Two Channel analog device with 3 polarity settings, Positive, Negative, or BiPolar. The device has adjustable Pulse Rate 0.5-120Hz, Pulse Duration 1-3s, and Micro / Milliamp Control. The unit is powered by one 9-Volt battery. Unlike traditional TENS units, MicroCurrent MENS output is at a lower level, and therefore the stimulation is often not “felt” or perceived by the patient. Includes Lead wires 4 Electrodes Battery Instruction booklet Carrying case Specifications Size 3.9 x 2.75 x 1 Weight 4.6 oz Channels Dual Waveform Symmetrical square biphasic MENS Pulse Rate adj. .5 120 Hz Carrier Frequency 14,000 cycles Polarity Positive, negative or bipolar with 1, 2, or 3 second adjustment within each range Output Current 0 5mA adjustable 0 1000 A Output Voltage 0 2.5 Volts peak to peak Power Supply 9 Volt Battery 1 Each / Each