The Gerbing 7V Full Foot Heated Sock Liners deliver warmth of up to 150°F for up to 7 hours. The Microwire heating elements cover both the tops and the bottoms of your feet for maximum warmth during all of your winter activities. Moisture-wicking 87% polyester/13% spandex fabric keeps you dry and comfortable. Touch-button temperature control is easy to use. Over-the-calf design. Includes two 7V, 2,200mAh rechargeable batteries and a dual charger. Imported.Manufacturer style #: GER-SKLN-7V. 87% polyester/13% spandex Reaches up to 150°F for up to 7 hours Microwire heating elements cover the tops and bottoms of your feet Moisture-wicking and comfortable Touch-button temperature control Over-the-calf design Includes 2 rechargeable batteries and a dual charger