Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 209403 found under Nut Plain Hexagon by United Brass Works Inc. The National Stock Number assigned to this part is 5310013800842, and the Federal Supply Class is 5310 Nuts And Washers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 209403.