This wool blend battery sock, with reinforced toes and heel, is the ultimate foot warmer indoors or out. 9 volt batteries are easily hauled in Velcro-closed pouches, keeping your feet warm, and you comfortable all day long. Maximum warmth for extreme weather Great for work, outdoor use, and uniforms Uses 9 Volt replaceable battery Wool Blend: 69% Acrylic / 19% Polyester / 2% Wool /1% Rubber 1 Pair NOTE: Please remember to remove battery before washing item