Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number D40SK45 found under Sprocket Wheel by Martin Sprocket And Gear Inc. The National Stock Number assigned to this part is 3020004281023, and the Federal Supply Class is 3020 Gear Pulley Sprocket And Transmission Chain. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like D40SK45.