Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number AE21-38-4-4 found under Bearing Sleeve by Bethlehem Steel Corp. The National Stock Number assigned to this part is 3120003173453, 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 AE21-38-4-4.