These are the wool-blend, battery-powered socks that soothe your feet with warmth, even on the coldest days. Made by the World’s foremost supplier of military outdoor clothing and gear, a heating element integrated into each sock provides up to six hours of gentle warmth to the feet when you’re out for a walk, shopping, or engaging in winter sports. The low-amperage element is located in the padded area of each foot and is thin and undetectable and the battery compartment and power button is in the cuff. Each sock requires one D battery. Made of 36% Wool, 33% Acrylic, 22% Polyester, 9% Nylon. Made in the U.S. Gray. Unisex sizes M (Men's 5-9, Women's 6-10) and L (Men's 9-12, Women's 10-13). (10 1/4 oz.)