This Paddock Boot Sock is made with NatureSpun Wool®. It has a slightly higher cuff than the Coolmax Paddock Boot Sock, and it is just the right weight to add warmth without any bulk.  Nature Spun Wool® is made from an intimate blend of Merino Wool and 100% post-consumer, recycled polyester and 100% post-consumer, recycled water & soft drink bottles.  MADE IN THE USA.