Duofold by Champion Men&rsquo;s Full Button Front Base Layer Union Suit, Red, L 2-LAYER 6.3-OZ. FABRIC: 100% cotton inside; 65% cotton/25% Merino wool/10% nylon outside Importado All-in-one slip comfortably smooths out all your trouble areas. Its timeless style pairs nicely with todays layered looks. Tried-and-true construction fuses two layers of fabric to create the feel of a single layer. An outer layer of cotton and Merino wool blend provides superior warmth. A layer of pure cotton against skin for softness and comfort.