This easy-to-use Portable Tens Unit uses Electrical Muscle Stimulation (EMS) for safe, effective, drug-free pain relief. Great to use on your back, shoulders, legs and arms, it produces a stimulating, pulsating massage that helps prevent pain signals from reaching your brain. It can also be used to complement exercise routines, increase endurance and help you relax. Customize your use with 6 treatment options, 24 therapy modes and 20 levels of intensity. Comes with 8 reusable electrode pads (4 large, 4 small) and a USB cord for recharging. Plastic, rubber and steel. Approx: 3 1/3"L x 2"W x 1/3"H.