I first purchase these socks in large size since I wear 11.5 size shoes and they provided excellent over the calf support (rating 5); however, when I purchase more I selected the medium size. The medium size socks were totally different and do not provide the same quality and amount of over the calf support provided by the large size socks (they were woven differently and from different cloth. While I can recommend the large size as far as support, I can't recommend the medium size because they are totally different socks and don't provide the quality of support.