Features: USB electric heating insole providing warm and comfortable feet experience. Featuring 7th generation black color , suitable for foot size 35 to 40; USB power supply, easy to connect to the power supply; with 3-speed temperature adjustment function to meet different needs; Soft, comfortable and breathable; waterproof , easy to clean. Suitable for long time outdoor activities, winter sports, residents of cold area and other people who need to keep warm. Can be used in outdoor activities, skiings, hiking, office and other scenarios to provide warmth and comfort. Specifications: Product Name: Remote Control Heating Insole Battery: 2000mAh Charging voltages: 5V1A Charging current: 400mA 7.4WH Discharging current: 4.2V 547mA 3.85V 505mA Operating voltages: 3.85V/4.2V Size：about 32x11x5cm/12.6x4.33x1.97in Load impedance: 8ohms Working discharging time: High temperature: around 55℃ for 4hours, Medium temperature 75%: around 50℃ for 6hours Low temperature 40%: around 40℃ for 9hours Optional Type：35 to 40 ； 41 to 46 Optional Package Includes: 1Pair Feet Heating Insole note: Please allow 1-3mm error due to manual measurement.Please make sure do not mind before bid. The color may have different as the differences display,please understand.