I wear this skiing under my helmet. There is mesh over the mouth area, which is the best facemask I've tried for skiing of all the ones i've tried. It allows you to breath well, and doesnt accumulate moisture like most facemasks. At lunchtime after a morning of skiing hard, the nosepiece was actually the only part that was a little damp. I dried it off but just wiping it hard with a cotton shirt for a minute or 2 and it was very comfortable to put back on for the afternoon (usually its miserable to put facemasks/neckwarmers on after lunch).
This facemask was very warm, windstopping, yet very breatheable. If its cold out and I find myself too warm, I prefer to open vents or dress lighter under my jacket so I can keep this thing on as opposed to heavier under my jacket and no facemask, and it works fantastic. Personally I don't find it super comfortable just pulling down the front facemask part so its not over my face but still on, i'll just take the whole thing off before doing that.
Great buy, and i'm very picky with neckwarmers/facemasks.