Duofold Men's Silkweight Dri-release Bottom 81% polyester, 14% cotton, 5% spandex Imported base-layer-underwear closure Machine wash cold with like colors. use only non-chlorine bleach when needed. no fabric softener. tumble dry low. do not iron. Dri-release technology dries 2.5x faster than cotton. All seams with flatlock stitching Great moisture control