Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number BL644 found under Chain Leaf by Jeffrey Chain Lp. The National Stock Number assigned to this part is 3020014362288, 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 BL644.