Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 21304 found under Connector Tubing Straight by National Oil Well. The National Stock Number assigned to this part is 4730013480728, 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 21304.