1. Improve the coldness of the feet, the carbon fiber material heats up, effectively stimulates the blood circulation of the feet, and helps resist the cold weather 2. Fast charging and long use time, charging for 4 hours and using for 10 hours. 3. It is suitable for people who work outdoors, must travel in severe winter, the elderly, people who are cold and afraid of cold. How to use: Button operation on the insole: 1. Before putting in the insole, press and hold the switch button for 3 seconds, the LED indicator light will be on, and the red light will be turned on, indicating high temperature. 2, and then click the LED blue light to light up, indicating medium temperature. 3. Click again, the LED green light is on, indicating low temperature. Tap to cycle red, blue, and green lights, adjust to three levels of high, medium, and low temperatures, and press and hold for three seconds to shut down. All Products From Us Have Undergone Strict Quality Checks. if There Is Any Quality Problem Or You Are Not Satisfied With The Product contact Us. we Will Give You The Best Solution.