Love these socks, bought a pair after going through countless others that weren't right and couldn't be happier. I wear a women's size 11.5-12 so I got the Large. These are great for hiking, thin enough on top to not be bulky but with the nice cushion on the bottom. My feed don't get too sweaty and best of all, they don't slide down. I bought 3 more pair, they are so good.