Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 40.21.307 found under Band Wire Strand by Sepson Ab. The National Stock Number assigned to this part is 4030011740421, and the Federal Supply Class is 4030 Fittings For Rope Cable And Chain. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 40.21.307.