To fit chest (recommended): S 33"-37", M 37"-41", L 41"-45", XL 45"-49", XXL 49"-53". Battle Dress Uniform (BDU) is the military uniform that the Armed Forces of the United States have used as their standard uniform for combat situations since September 1981. The shirt is made of prewashed cotton Ripstop material which is extremely hard wearing and the most durable material you can get combat clothing in.