Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number D251-8B found under Parts Kit Diaphragm Replacement by Henry Technologies Inc. The National Stock Number assigned to this part is 4820000361322, 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 D251-8B.