The Boot Liner Crew by Carhartt is a 9-inch tall boot liner made of 100% acrylic fabric that provides lightweight warmth and wicks away moisture. It features a crew neck, rib-knit cuffs, and a tagless label for comfort. This Carhartt boot liner is machine washable and made in the USA. It comes in sizes S-3XL in black, carbon heather, or dark brown heather.