Liang Rou Men's Fleece Lined Thick Thermal Pant Elastic closure One Piece Ultra Warm Fleece Lined Thermal Bottoms Elastic Fabrics. 93% Cotton 7% Spandex. Lining 100% Polyester Fibers. Ultra Soft, Comfortable and Warm. Not bulky. Great to wear alone at home or add an extra layer of warmth under your clothes Please choose the suitable size according to the size chart (in Product Description).