SIZE: Adult snug fit, One SIZE fits most. Also fits Juniors and Teens; Dimensions - 10.25"(W) x 7.5"(L). Weight - 1.5 oz. BUILT FOR PERFORMANCE: Made with our Comfort Shell Stria Performance fabric - 88% polyester, 12% spandex. It works to manage moisture and maintain heat, while also providing UPF 50+ sun protection. NO OVERHEATING: The Brain Shroud easily wicks away sweat and moisture from your head, making it breathable and quick-drying – perfect for every inside or outdoor adventure. CLEANING MADE SIMPLE: Time for a wash? Just throw it in the wash on cold, tumble dry on low heat and it's ready for its next use. SKULL CAP OR HELMET LINER: A great option as a standalone cap, under a bike or ski helmet, extra coverage on the xc ski trails, cold weather runs or wherever your adventures take you. With single-layer coverage at the crown and double-layer coverage at the ears, these snug-fit skull caps are moisture-wicking, breathable, and quick-drying, making this hat a great option for all of life's adventures, big or small.