Originally Posted by PaulRivers

Yeah, the one I had that worked relatively well, the piece was like a headband that went over your nose/mouth.
Problem is, that covers a narrow range of maybe 5-15f. Once you get to 5-10f you get into the range where any exposed skin is vulnerable to frostbite. Keep in mind you're riding into the wind of course. So having something that might leave some skin exposed is...iffy.