The unique Temp-Dry Technology allows for these caps to be used in any weather including those Cold winter night or hot summer days. Wicking away the sweat in the summer and retaining the heat in the winter Keeping your head and ears nice and warm. "Stretchy, breathable material, allows the temple tape Skull cap to fit virtually every head size and shape.We Created the Temp-Dry material to be super Slim and light weight allowing this skullcap to fit under any Hardhat or helmets such as: Motorcycle helmet, Ski Helmet, Football Helmet, Bike helmet, Baseball hard hat, Hockey face mask, snowboard helmet, bike and bicycle helmets." The outer layer of the hat provides the moisture wicking abilities. The inner Layer of the hat is lined with a super fine brushed fleece which provides the thermal retention, keeping you warm during your outdoor winter workout. Perfect for sports such as cycling, hunting, biking, skiing, snowboarding, riding and wrestling, Pairs perfectly with goggles or any type of eye gear. This Skull cap is designed with our Temp-Dry fabric allowing it to absorb and evaporate sweat, preventing the sweat from dripping in your eyes. The lightweight material and the moisture wicking capabilities combined with the thermal retention come together to bring you the perfect headwear for any temperature. One Size Fits All – Big head... Small head… No problem! This skullcap beanie is designed to fit on any shaped head, including mens, womens and even kids. Our Temp-Dry anti-tear material is light weight, flexible and super durable. Great every day, Christmas or holiday gift for your husband, wife or even friend