Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number U1688 found under Valve Automatic Con by Siemens Water Technologies Corp. The National Stock Number assigned to this part is 4610004242768, and the Federal Supply Class is 4610 Water Purification Equipment. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like U1688.