Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number AT489B3 found under Pilot Counterbore by Snap On Tools Corp. The National Stock Number assigned to this part is 3460009323309, and the Federal Supply Class is 3460 Machine Tool Accessories. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like AT489B3.