Seirus Neofleece Combo Face Mask / Scarf is a face and neck warmer combined all in one. It is the #1 selling face mask in the world! The Neofleece construction places a warm soft fleece next to your skin and an outer layer that is waterproof and windproof neoprene. The mask is Velcro adjustable. But they fit slightly large so if you are in between on your size, go down a size. The best rule of thumb is as follows: XS - children, S - big children, small women, M - teens, women, L - men