Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number AT520D found under Swaging Machine Rotary Electric by Snap On Incorporated. The National Stock Number assigned to this part is 3446012240939, and the Federal Supply Class is 3446 Forging Machine And Hammers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like AT520D.