This thing, if you want warm. It's called the Seirus Ultra Clava. You can just use it as a mask, just use it as a balaclava-hood thing, just use it as a gaiter, or use it normally.
It's up to you, it's super warm and doesn't fog. I don't know, as I look pretty silly here:
Overall, warm and nice. Can wear it multiple ways. $25.