Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 528-1 found under Diaphragm Valve Flat by Sealco Air Controls Inc. The National Stock Number assigned to this part is 4820001015124, 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 528-1.