So I've used the Cat Crap stuff for a few rides now, ranging from 50 degrees to 15 degrees. Wearing my sunglasses (which tend to fog up when stopping even during the summer) fog up pretty much just as bad with my mouth/nose mask on. It works really well for times like when you come in from the cold into heat, but other than that... I'd say for the cold to hot transition the stuff is still worth the money actually, it's only like $6 a can, but don't expect it to work miracles if you're fogging up while riding.