Check the listing for details. US Military Polypropylene Cold Weather Undershirt Polypro Shirt Medium 295-D. Listed at 20.66 USD. Undershirt, Cold Weather 100% Polypropylene. This is a genuine U.S. Military, polypropylene, cold - wet weather shirt. Polypropylene is also color fast, so it will resist fading and continues to look good, even in chlorinated climates.