Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number ASTM B221 found under Retainer Seal by American Society For Testing And. The National Stock Number assigned to this part is 5330011844898, and the Federal Supply Class is 5330 Packing And Gasket Materials. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like ASTM B221.