Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number F 637 31 2 1 2IN 1STEM found under Stem Fluid Valve by Nibco Inc. The National Stock Number assigned to this part is 4820012828552, 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 F 637 31 2 1 2IN 1STEM.