Medium Sock Sizing Information: Women's 7-10 / Men's 6-9 Lightly cushioned for comfort, our Lightweight Merino Performance Crew Socks are designed for a long life on the trail. The RWS-certified wool/nylon/spandex blend offers exceptional breathability, rugged durability, and excellent stretch and recovery that lasts the lifetime of the socks. All of the virgin wool Patagonia sources is certified to the Responsible Wool Standard (RWS) from farm to fiber to help ensure protection both for the animals that supply it and the land they graze.