Level 1 of the ECWCS system. Highly breathable moisture wicking, 4 ounce GI plus 100% polyester jersey knit fabric. Fabric helps wick moisture away from skin. Features PISOFT AB-500, durable anti-odor and anti microbial properties, improves elasticity and tear strength and pill resistant and anti-static. Features: Elastic waistband, access fly. Black colored bottom. Military E.C.W.C.S. generation III silkweight underwear. ECWCS, short for Extended/Extreme Cold Weather Clothing System. Black - generation III silk weight bottoms. Meets or exceeds military specification.