Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B2251-4 found under Valve Check by Ajax Magnethermec Corp. The National Stock Number assigned to this part is 4820002886678, 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 B2251-4.