These do a great job of keeping my feet toasty. I wear a size 7 boot & bought the smallest size fleece boot sock to wear with my off brand (kamik) rain boots. I don't know if its the slender cut of the boots (they are not roomy) or the large size of the hunter boot sock, but I can not get these on without dealing with bunching and folding-up of the sock down in the boot by my feet. Because of that annoyance they have only been worn twice on snow days. But they did a great job of keeping my feet warm. Maybe if I tried them with some more roomy boots itd work out better?