Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number MS21913J4 found under Plug Tube Fitting Threaded by Zeller Corp The. The National Stock Number assigned to this part is 4730000531919, and the Federal Supply Class is 4730 Hose Pipe Tube Lubrication And Railing Fittings. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like MS21913J4.