These are fantastic shoe covers. A size L/XL fits my 43.5 Specialized shoes great. Not too tight, not too loose. So far, I've worn them in temps ranging from 35-55F, and they are great all throughout that range. They do get a bit damp from sweat on the high end of that range, but I never noticed until the end of the ride when I took them off. Feet have never been cold with these on and they block out the wind great! If you want warm feet on chilly rides, just get these. Plus, they look rad.