Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B39-71021 found under Seat Valve by Newport Scientific Inc. The National Stock Number assigned to this part is 4820001403707, and the Federal Supply Class is 4820 Valves Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like B39-71021.