Salco Products (TE4S416SU29A) 4-Inch Thread On Stainless Steel Quick Connect Assembly, Black Peroxide Cured EPDM Gaskets fits a 5-1/4-inch rail road thread. The 4-inch quick connect adapter is made out of 316 stainless steel, and features a 4-inch cam groove along with 5-1/4-inch-4 Special 2A threads. The adapter comes with a 3/8-inch, 18-8 stainless steel, chain with 15 links, a 3/8-inch by 3-1/2-inch, 18-8 stainless steel, S-hook, a 3/8-inch by 1-3/4-inch, 18-8 stainless steel, hex bolt, a 3/8-inch, 18-8 stainless steel, lock nut with two 3/8-inch, 18-8 stainless steel, flat washers, and two 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 416 stainless steel and features 5-1/4-inch-4 UN-2B threads along with a 1-inch NPT, 316 stainless steel, plug assembly. The plug assembly Includes a 1/4-inch, 18-8 stainless 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, 18-8 stainless steel, S-hook, a 304 stainless steel lock ring that connects to a 3/8-inch, 18-8 stainless steel, chain with a 3/8-inch by 2-1/4-inch, 18-8 stainless steel, hex bolt, a 3/8-inch, 18-8 stainless steel lock nut and two (2), 18-8 stainless steel ,flat washers. Length of chain is 15 links which is approximately 21-inches long. The quick connect assembly is about 9-inches high and comes with black epdm gaskets for the cap and adapter. AAR Approval # E-149523. Approved for DOT Stenciled Cars.