Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number MB4550DU found under Bearing Sleeve by Krauss Maffei Wegmann Gmbh And Co. The National Stock Number assigned to this part is 3120121727031, 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 MB4550DU.