I have both Toester Bootie and the AmFIB. For me the AmFIB worked good for anything over 35. Ive been wearing the Toester lately and its been in the high teens when I leave for work and low teens when I come home. With these booties all I wear are shoes underneath no socks. By the time I get home which is about an hour and a half my toes do start to get cold. I think with a good pair of wool socks on you would have no problem, and if you want to get real high tech you could put a plastic bag over you shoe and under the bootie.