Spandex Sweat Beanie, Use as a Helmet/Hat Liner, Sweatband Skull Cap - Polyester 87% Polyester and 13% Spandex Functional extra layer to add warmth when needed - Think long underwear for your head! Thin black beanie skull cap to be worn under your hat or helmet Created from polyester spandex blend for a snug fit that helps retain warmth One size fits most up to 24 inches. Measures aprox. 9 inches long by 7.5 inches wide when laying flat Available for a limited time only. Makes a great gift this season!