Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number FSW 666B.5625 found under Valve Assembly Manifold by F S Welsford Company. The National Stock Number assigned to this part is 4820014465908, 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 FSW 666B.5625.