The Outrek II Heated Insoles feature the most sophisticated heating technology that is sure to keep your toes warm. Each insole has a thin, built-in rechargeable battery. With the insoles in your boots, use a handy remote control to turn the heat on and off or adjust to the perfect temperature. The heat reaches up to 140°F and can last up to 6 hours. Use these insoles in any shoe or boot and keep your feet will be warm and happy all day long.