I use this for my 4 mile commute under my cycle helmet and it keeps my face and especially my ears warm, it's thin enough that it doesn't interfere with the helmet.  I wear glasses so I much prefer this design that's open around the nose so that i don't get fogging.  I ended up buying a second one so that I can throw one in the laundry basket each week. folds and rolls up small when not in use so you can stuff it in a pocket.