Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number H521-2 found under Adapter Straight Pipe To Hose by Rostra Vernatherm Llc. The National Stock Number assigned to this part is 4730010165035, 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 H521-2.