Mens Knitted Thermal Heavy Winter/Ski Hat (3M 40g) Acrylic, Polyester, Great quality warm thinsulate hat, ideal for cold winter days, fishing or the ski slopes. Fiber: Outer 50% Acrylic 50% Polyester, Interlining c40 premium thinsulate, Lining 100% Polyester. Machine washable. Ideal for wearing in the cold weather. Keeps your head nice and warm.