Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 5400519-4 found under Valve Check by Harris Environmental Systems Inc. The National Stock Number assigned to this part is 4820012495309, 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 5400519-4.