This fully lined sea otter fur hat with a seal fur exterior shell on it is waterproof and windproof. The beaver on the front is unique because it does not freeze and gives the hat an even more exotic look. My hats are are used in the Iditarod by 20 time veteran Ramey Smyth. He also wears my Mittens, if you nca imagine, this guy trusts my gear to keep him warm in up to negative 50 weather with 50 mile per hour winds. Pretty cool!!!