Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 429 20 found under Spring by Bureau Of Mines Helium Operations. The National Stock Number assigned to this part is 4820009561191, 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 429 20.