Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 283550-1373 found under Valve Check by Atlantic Inertial Systems Inc. The National Stock Number assigned to this part is 4820012004993, 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 283550-1373.