TCK Player Id Number Crew Sock (SINGLE SOCK) - Navy/Carolina Blue/White 93% nylon, 5% elastic, 2% lycra spandex. Sold as a single sock. Moisture and blister control. Arch compression. Breathable mesh. Ergonomic cushion. Double welt top. The player ID sock was designed to allow players to pick and choose 2 individually packaged socks to combine into their own unique number or player ID. 93% nylon, 5% elastic, 2% lycra spandex.