Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 639-02 found under Parts Kit Pressure by Norgren C A Co. The National Stock Number assigned to this part is 4820011377201, 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 639-02.