adidas Boy's Copa Zone Cushion Sock (Black/Infrared, Small: Youth Shoe Size 13C-4Y) Nylon, Spandex Imported Added compression in ankle and arch for excellent stability. Extra Small fits youth shoe sizes 9C-1Y Small fits youth shoe sizes 13C-4Y Medium fits men's shoe size 5-8.5, women's shoe size 5-9.5 & youth shoe sizes 4Y-212 Large fits men's shoe size 9-13 and women's shoe size 10-218