Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B1549-04 found under Valve Check by Aerocontrolex Group Inc. The National Stock Number assigned to this part is 4820011527500, 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 B1549-04.