Got this as a freebie with a pair of approach shoes. They fit small (medium supposedly fits up to size 8.5 which is my running shoe size, but they were too small) so I gave them to my wife (size 6 womens and they fit her fine), but even if they fit me I would not have used them for running. Too thick --- I prefer using super thin acrylic socks for running.
This review was written in the old system and had content requirements that are different than reviews written today.