Polypro long underwear bottoms are part of the military ECWCS system. This is the base layer that goes under the fleece liner (bear pants) and the Gore-tex pants go over the fleece liner. These pants are very warm and wick away moisture from the body better than most fabrics! Used bottoms are available in brown only. These polypro bottoms are used and in good condition but may be shrunk a size from being in a dryer, so you might buy a size larger than you normally would!