ColdPruf Men's Authentic Dual Layer Wool Plus Base Bottom 100% Other Fibers Imported Inside -100% cotton, outside - 50% cotton, 40% Merino wool, 10% nylon, imported Flat seams, tag less and front and back rise for comfort True sizing for accurate fit with gussets and comfort waistband Thermachoice system: extreme cold weather/low to medium activity Ring spun yarns provides exceptional softness