Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 4DP 2039 B21 SIZE 1 1 2 found under Seal by The Walworth Company. The National Stock Number assigned to this part is 5330010531697, and the Federal Supply Class is 5330 Packing And Gasket Materials. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 4DP 2039 B21 SIZE 1 1 2.