Buy these socks or you will end up up an alternate timeline where Biff rules all. Cool Socks Men's Crew Socks - Back to the Future are 87% polyester, 10% cotton and 3% spandex. Fits shoe sizes US 6-13. Socks are slim and lightweight with a light cushioned heel to ensure a secure fit. Machine wash warm & tumble dry low. Do not bleach or iron.