Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number R4001 2IN found under Valve Angle by Robert Manufacturing Company Inc. The National Stock Number assigned to this part is 4820006050723, 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 R4001 2IN.