Even in the most bitter cold, these heated wool and Thermostat socks provide soothing warmth. Thermostat is made from hollow-core fibers that trap air while moving moisture away from skin. A battery-powered heating element in the padded area of each toe has low and high settings and won't overheat. The low-amperage element is so thin as to be undetectable. Socks run 12 hours on low and 10 hours on high setting. Gray. Requires two D batteries. Made of 40% Wool/40% Acrylic/20% Polyester. Imported. Unisex sizes (see the Determine Size tab below) M, L, and XL. (9 oz.)