thorlos Padded Extreme Cold Over The Calf Socks 100% Other Fibers Made in US No Closure closure Machine Wash Thorlos clinically-tested padding under the ball and heel provides maximum protection from friction, the Primary cause of blisters, and impact protection where needed most Performance Fabric: Constructed with thermal worsted wool and THOR LON fibers for superior softness, resilience, durability, and moisture-wicking for drier and better feeling feet. Made in Statesville, North Carolina, USA 30 Day Guarantee: Thorlos feel better than ordinary socks. If you do not agree, send the socks and your receipt to Thorlos for a full refund. 60%worsted wool , 26%exclusive THOR-LON acrylic , 11%nylon , 3%elastic