Marshall Excelsior (ME952-07 LP OPD Filler Valve Dust Cap and Strap MARSHALL EXCELSIOR LP OPD Filler Valve Dust Cap and Strap - Designed to protect the 1.32 inch male Acme threads on Type 1 (QCC) or OPD type cylinder valves Using a cap will reduce the likelihood of inadvertent damage to the cylinder threads, shutoff mechanisms and sealing surfaces during storage or refurbishment