Quote Originally Posted by JohnSawyer View Post
I think it's called Warm Window... http://www.warmcompany.com/wwpage.html It's pretty heavy, though.

I've used Insul-brite, and Insultex. For a hat, I'd go fleece, some insulator, and a ripstop windproof shell... I'm not sure a vapor barrier is a good idea on your head...
I can see it in a hood, maybe, as long as it wasn't cinched down tight.