Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 5231-9000-20 found under Valve Stop Check by Clean Earth Environmental Group Inc. The National Stock Number assigned to this part is 4820013517167, 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 5231-9000-20.