Warmawear Deluxe Wireless Rechargeable Heated Insoles with Remote Control - Small Wireless battery system is built into the insole so there is no need for an external battery box strapped to the ankle Far-infrared heating element gently warms the toes and surrounding area which are the areas most susceptible to cold Insoles can remain warm for up to 7 hours, depending on selected temperature setting-this time can be dramatically increased by switching them on for short bursts USB charging cable allows you to recharge insoles using a PC, laptop and more Three heat settings, so you can select the temperature best for you