Debra Weitzner Mens Thermal Underwear Set Crew Neck Top/Long Pants Grey XL 65% cotton/ 35% polyester 2-piece mens thermal underwear set features crewneck to with long sleeves and long johns pants. Thermal underwear features a cotton-polyester-blend fabric with a box-weave texture. Thermal set for men provides utomost protection against the cold Available in 4 sizes and 3 colors.