More than 25% of body heat is lost through the head and extremities of the body. The Sharkskin Chillproof beanie uses Chillproof material over 90% of the head area to keep you warm and provide protection from windchill for paddling and board watersports, and power watersports like jetski and boating, and wind watersports like sailing. Includes a comfortable ‘micro fleece' band for superb fit over your ears and to allow for hearing.