Salco Products (TE4IU3A) 4-Inch Thread On Ductile Iron Quick Connect Assembly, Black EPDM Gaskets fits a 5-1/4 inch rail road thread. The quick connect adapter is made out of ductile iron, and features a 4-inch cam groove. Includes a 3/8 inch, carbon steel, chain with 15 links, a 3/8 inch by 3-1/2 inch, zinc plated carbon steel S-hook, a 3/8 inch by 2 inch, zinc plated carbon steel, hex bolt, a 3/8 inch, zinc plated carbon steel, lock nut with two (2) 3/8 inch USS, zinc plated carbon steel flat washers, and two (2) 3/8 inch by 1/2 inch, 18-8 stainless steel, socket cap screws. The 4-inch, quick connect, thread on cap is made out of ductile iron and features 5-1/4 inch -4 UN -2B threads along with a 1 inch NPT, carbon steel, plug assembly. The plug assembly includes a 1/4 inch, carbon steel, chain of 15 links with an approximate length of 19 inches. The thread on cap comes with a 3/8 inch by 3-1/2 inch, zinc plated carbon steel, S-hook, a 304 stainless steel lock ring that connects to a 3/8-inch, carbon steel, chain with a 3/8 inch by 2-1/4 inch, zinc plated carbon steel hex bolt, a 3/8 inch, zinc plated carbon steel lock nut and two (2), 3/8 inch USS, zinc plated carbon steel, flat washers. Length of chain is 15 links which is approximately 21 inches long. The quick connect assembly is about 8 inches high and comes with Black EPDM gaskets for the cap and adapter. AAR Approval # E-149523. Approved for DOT Stenciled Cars.