Now you can get fast, drug-free pain relief for sore, aching muscles and joints. TENS therapy delivers safe electrical pulses to stimulate the production of endorphins – the body's natural pain killers. This lightweight and portable TENS massager easily connects to your smartphone, tablet or any USB power source. Simply plug it in with the micro USB lightning connection cord included, and choose from 8 different intensity levels of stimulation – no batteries or charging is required! The unit cycles through 6 pre-programmed massage modes that change every 5 minutes. Includes carrying case and 4 reusable gel pads to place on your back, shoulders, arms, hips or legs. 6"L x 4'W x 1 1/2"H.