Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 668416-021 found under Packing With Retainer by Parker Hannifin Ltd. The National Stock Number assigned to this part is 5330002033749, 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 668416-021.