Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 0491C0003 found under Valve Safety Relief by Martin Marietta Technologies Inc. The National Stock Number assigned to this part is 4820012003384, 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 0491C0003.