JOBMAN Workwear Men's Underwear Top-Round Neck 100% Polypropylene Imported Machine Wash The material Polypropylene is 40 times better at transporting moisture than polyester Polypropylene absorbs 0.01 percent moisture(polyester absorbs 0.6 percent and wool 30 percent moisture) A material weight of 240g means larger air pockets (microclimates) and better insulation High elasticity means the garment remains fitted to the body, which maximizes moisture wicking