Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number AT520CT-28 found under Bleeder by Snap On Incorporated. The National Stock Number assigned to this part is 5130011270255, and the Federal Supply Class is 5130 Hand Tools Power Driven. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like AT520CT-28.