Product Material: cotton cloth + carbon fiber Size: (flexible) sole length, 20 cm; sock length: 23 cm; sock opening: 9 cm Battery voltage: 3.7 V Battery capacity: 2200 mAh Temperature control: 3 levels adjustable Temperature: low-end, 35 degrees Celsius; mid-range, 45 degrees Celsius; high-end, 55 degrees Celsius Color: gray, black Quantity: 1 pair Package content: - 1 pair heating socks (with battery and charger) 1. Battery Operation & Heating Elements To give your feet a more balanced warmth, our heated socks feature enlarged heating elements on the toes and soles. Keep your feet warm all day when fully charged. The adapter light turns red during charging and green when fully charged. 2. 3 Adjustable Temperatures Electric foot warmer with 3-stage temperature settings. The heating range is between 35°C and 55°C. The red LED indicates high temperature, the orange LED indicates medium temperature, and the green LED indicates low temperature. 3. Flame Retardant Safety Cotton The heated socks are made of cotton, polyester, and spandex. The breathable, quick-drying, flame-retardant cotton ensures safety during use. The far infrared heating elements help stimulate blood circulation. 4. Washable and One Size The socks are hand wash and machine wash friendly. Please remove the battery and cable before washing. One size fits most adults, men and women, with a stretchy and comfortable fit. 5. Widely Used & Great Gift These electric socks are suitable for various indoor or outdoor activities such as hunting, hiking, horse riding, fishing, biking, driving, running, camping, skiing, climbing, and sleeping. They make a great gift for parents, friends, family members, and the elderly.