Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 399-03B found under Piston Valve by Magnatrol Valve Corporation. The National Stock Number assigned to this part is 4810013689502, and the Federal Supply Class is 4810 Valves Powered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 399-03B.