4 Pairs Thorlos Walking Socks Medium Black Crew Unisex. This set of 4 crew length socks are all black. They are moderate cushion walking socks with exclusive thor-lon. The medium is equivalent to the US shoe size Men's 5.5-8.5 and Women's 6.5-10. These are wx-11 and are made in the USA. Constructed of 83% Thor-lon acrylic, 12% stretch nylon, 5% spandex. Walking protection level 3.