Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B3-H21 found under Coupling Half Quick Disconnect by Tuthill Corp. The National Stock Number assigned to this part is 4730006025342, 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 B3-H21.