Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 09-20000 ITEM NO. 21 found under Valve Plug by Young Engineering And Manufacturing. The National Stock Number assigned to this part is 4820015988182, 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 09-20000 ITEM NO. 21.