There are a lot of asses around here, so that's a pretty important title. Made with shock-absorbing cushion, soft heel tab, and compression band. S/M fits women's shoe size 5-9/men's shoe size 4-8. L/XL fits womens's shoe size 9-13/men's shoe size 8-12. 39% polyester; 39% cotton; 19% nylon, 3% spandex.