The TENS Intensity 7 is a muscle stimulator and muscle recovery device that provides prescription strength pain. Energized by a 9Volt battery, this TENS machine is proven to be powerful and durable. The TENS unit sends comfortable stim impulses through the skin that stimulates the nerve in the treatment area, acting as an electric massager, and calming the nerve. System includes device, lead wires, four self-adhesive reusable electrodes, 9V battery, hard plastic carrying case, quick start guide and instructional manual.