I must say, these things keep your feet warm. As a northern Minnesotan it easily drops in the negative temps for winter and wearing these my feet end up being the warmest part of my body even if I wear shoes with air vents. The only reason this is 4 stars instead of 5 is that after a while the fuzz in the inside clumps together in a few spots and becomes rather uncomfortable, it was easy to fix by just trimming it off though but I'm not sure what that does to the long term integrity of the socks. This only happened in one sock though and the other one has had no clumps so I'm hoping this is a nonstandard occurrence. Either way I would definitely buy this product again.