These are knee-high socks that have been plaited with spandex for shape retention. They're rib-knit with soft and cozy cotton yarn. Sizing S - Womens 4-6 M - Mens 6-8 / Womens 6-10 L - Mens 8-12 / Womens 10-13 XL - Mens 12-15 NIKE NIKE SLOUCHY CREW SOCK