The ActionHeat classic battery-heated socks provide the best quality and comfort. The ActionHeat socks reach a maximum temperature of 130F and can last up to 4 hours. ActionHeat battery-heated apparel utilizes innovative technology designed to warm the core body temperature. These revolutionary garments feature built-in heating panels and are made with ActionFlex material that provides lightweight warmth, comfort, and versatility.HOW TO USE: Power Up - Insert (3) AA batteries into each power pack. Plug-In - Connect the power pack to the cord located in the pocket on the top of the sock. Turn On - Press the red power button on the power pack. Features: Built-In heating panels strategically placed on the top of the toes use advanced ultra-fine fibers to provide superior heating performance Battery Voltage: 4.5 Volt Power Packs Power System: AA Batteries (not included) Colors Available: Black, Grey Recommended hand wash only. Note: Can use a mesh wash bag for gentle machine wash. Heats 4+ Hours Unisex Fit Sizes Available: S/M, L/XL, XXL Estimated Heating Times:Heats up to 130F for up to 4+ hours.Material Contents:Material Content: 70% Cotton & 30% SpandexIncludes: (2) ActionHeat Cotton Blend Socks (2) AA Power Packs; Each requires (3) AA Batteries (Batteries Not Included)