Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number H6641 1 4S28 found under Valve Regulating Fl by Teledyne Technologies Inc. The National Stock Number assigned to this part is 4820014499424, 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 H6641 1 4S28.