The Salco Products (TC43BCDI3A) 4-Inch Ductile Iron Bottom Outlet Cap with Black EPDM Gasket and Carbon Steel Chain is made out of ductile iron material with a 3-inch carbon steel/ ductile iron plug. It fits a standard 5-1/4-inch railroad thread for application to any car manufacturer's nozzle. Comes with 3/8-inch, carbon steel, chain, a 4-inch, 304 stainless steel lock ring, a 3/8 by 2-1/4-inch, zinc plated carbon steel, hex bolt, a 3/8-inch, zinc plated carbon steel, hex nut lock, a 3/8-inch USS, zinc plated carbon steel, flat washer, and a 3/8 by 3-1/2-inch, zinc plated carbon steel, S hook. This model includes an easily replaceable black EPDM gasket that is 1/4-inch thick with a 3-1/2-inch inner diameter and a 5-1/4-inch outer diameter. This cap is not AAR approved to travel with car