Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B And L BLOCK CO.FIG 4241 found under Pulley Groove by Apex Tool Group Llc. The National Stock Number assigned to this part is 3020009271617, 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 B And L BLOCK CO.FIG 4241.