The Vital Stim EMS 400 unit has two outlets known as channels. Each channel has two wire connections with two pads attached at the end of each wire. The EMS unit delivers a gentle electronic impulse to your muscles via the soft electrode pads that come with your system. By placing the pair of pads on a particular muscle group, your muscles respond to the impulses that are generated by contracting and relaxing rhythmically as instructed by you through the unit. When a muscle contracts as a result of a unique EMS/TENS signal, the chemical changes taking place within the muscles are similar to those associated with voluntary contraction in normal exercising. These chemical reactions which result from muscle contractions, utilize glycogen, fat and other nutrients stored in the muscle. The resulting series of muscle contractions will enable an individual to tone, strengthen, and combat flabbiness while improving contour. Just strap it on while you're resting, reading, net surfing or watching T.V. and watch your body transform right before your eyes. Dual Channel variable control unit includes Case, Electrodes, Battery, Manual, Pad Placement Chart, Lead wires, 12 Electrode pads (8 self-adhesive and 4 non-adhesive black rubber pads) and more. FDA Registered to meet U.S. Safety Standards. One year warranty.