For use with smart relief control unit (sold separately). Icy hot smart relief tens therapy refill kit includes 2 Electrode Pads and one 3V replacement battery. Easy to use, no wires, no assembly, no doctor needed. The electrical pulses of Smart Relief are generated by a small, battery-powered device. It's remarkably small - only half an inch thick and smaller than a credit card. It easily snaps onto an adhesive patch, and activates two small electrodes that pass the gentle electrical pulses through your skin and block your pain. It provides the same type of tens relief you find in physical therapy facilities. Smart Relief takes pain relief to a whole new level - 63 to be exact. You can easily raise or lower the intensity level to customize the relief you need. Just turn on Smart Relief, and turn off pain.