Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number D-1994 SIZE 1IN found under Valve Check by P J Valves Inc. The National Stock Number assigned to this part is 4820010924294, 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 D-1994 SIZE 1IN.