As I work from home, most of the time I wear orthopedic thong sandals ("flip-flops"). I decided to try these socks to see if they would keep my feet warmer during the heating season. They do that, although not as well as I had hoped. They also make it a bit more comfortable between the toes. I bought the largest size, which indicates it will fit up to a men's size 13 foot. I wear size 12 shoes and the socks are snug on me, so I would dispute their statement that the sizes run big. Overall they are suiteble, but not perfect.