USB Charging Heated Insoles: The heated insoles adopt new heating technology, made of soft and comfortable EVA stretch material, with good cushioning, portable lightness. The heater is comfortable with USB interface used for heating via the USB cable, large heating surface, even heat distribution, temperature up to 42 C/108 . Cleanable & Charging Use: This USB insole material has a waterproof effect, is washable and reusable, you can wash it with a brush, not for machine washing, it should be noted that it needs to be dried after washing and must be completely dry before use. Wide Range of Uses & Best Gift: The heated shoe insoles keep your feet warm during cold winter, the temperature reaches up to 42 C/108 , so no matter where you go, you can keep warm, suitable for skiing and outdoor sports, other sports, camping, chores, hunting, hiking, fishing etc, is the best Christmas gift.