Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number S1D10025 ITEM 4 found under Poppet Valve by Vacco Industries. The National Stock Number assigned to this part is 4820012161540, 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 S1D10025 ITEM 4.