Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number T138-4SS-1P found under Valve Stop Check by Teledyne Technologies Inc. The National Stock Number assigned to this part is 4820010593526, 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 T138-4SS-1P.