Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number R20978 found under Shim by Pressed Metals Of America Inc. The National Stock Number assigned to this part is 5365004959590, and the Federal Supply Class is 5365 Bushings Rings Shims And Spacers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like R20978.