ThermaCELL Heated Insoles ProFLEX is the extended solution to cold feet. These wireless, battery-powered insoles easily slip into your own boots or shoes. The included fingertip remote control lets you choose the heat setting. Charge batteries using the included wall charger or any powered USB port. Provides up to 5 hours of warmth per charge. Sizes MD (Men 5 ½-7, Women 6 ½-8), XL (Men 9 ½-11, Women 1 ½-12), 2XL (Men 11 ½-13, Women 12 ½-14).