Two-layer engineering Traps air between layers providing a natural barrier of warmth Full button front Union Suit with single button rear flap Inside Layer: 100% combed ring spun cotton Outside Layer: 65% combed ring spun cotton, 25% MERINO WOOL, 10% Nylon Fabric weight: 6.6 oz. Tagless design and flat seams provide smooth fit and extra comfort Soft cotton next to skin