Premium MaterialFlintronic Heated Insole is a latest high-efficiency carbon fiber heater that works with power banks. It is made of stretchy high-quality EVA foam, PU and plush surface, which is soft and comfortable, allowing your feet to relax without feeling tight. USB Heated InsoleThe heated insole has a USB interface for easy charging. The maximum temperature after heating can be as high as 55°C, and the duration of the temperature varies depending on the environment. (A battery is included in the product to store electricity.) You can put it directly into your shoes and enjoy the warmth when you put them on, which is very convenient. Remote Control TemperatureThe product contains a temperature control remote control. There are three levels of temperature adjustment: low temperature (40-45°C 104-122°F 10h); mid-range (45-50°C 113-122°F 6h); high temperature (50-55°C 122-131°F 4h), which can meet your diversification need. Free Cut SizeThe shoe size range is marked on the heated insole, which can be cut to the size you need to fit your shoes. The size lines are clear and precise and easy to cut, so you don't have to worry about cutting the wrong size insole. Wide ApplicationPower bank heated insoles, can solve foot problems in cold weather, keep your feet warm all winter without sweating. It has a wide range of applications, including many winter activities such as hunting, skiing, motorcycling, mountaineering or hiking. We firmly believe that the Flitronic heated insole must be the perfect choice for you!