ThermaCell Heated Insoles are designed to provide continuous warmth for up to five hours, or longer when used in intervals. These cordless, remote controlled, rechargeable heated insoles have a built-in thermostat. A high-tech wireless remote allows for fingertip control over heat levels. Each remote features a uniquely coded, highly reliable radio frequency transmitter that is paired to one set of insoles and has a range of seven feet. It can easily be attached to zippers and belts, or simply stored inside a pocket. The insoles can be customized to fit any shoe size from women's 4.5 to men's 13, and are available in small, medium, large, x-large, and xx-large.