1. Made of high-quality flannel composite fabric, it is light, soft, comfortable, highly insulated, and has a long service life. 2. As a necessary warming artifact for winter, it heats at a constant temperature (40°C) to provide comfortable warmth for your feet in cold weather and dispel the cold. 3. Universal USB interface. Compatible with various charging devices such as adapters, mobile power supplies, car USB interfaces, and computers. 4. The portable foot warming bag is easy to operate and can be used without charging or a self-supplied battery by connecting the USB interface, making it environmentally friendly. Specifications: Material: Flannel composite fabric Color: Gray USB cable: 5v=1.8a (9w) Net weight: 0.142kg Product dimensions: 29*29*2.5cm Packing: 34*30*2.8cm Packing list: 1* Foot warming bag 1* USB cable (attached to the product).