Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number AM421S4400-1022148-55 found under Bearing Sleeve by Ac Valve Inc. The National Stock Number assigned to this part is 3120012161419, and the Federal Supply Class is 3120 Bearings Plain Unmounted. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like AM421S4400-1022148-55.