Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B16.4 found under Reducer Pipe by American National Standards Inst. The National Stock Number assigned to this part is 4730002775650, 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 B16.4.