Series 770 Double Check Valve Assemblies were produced from 1993-1997. Although the device is discontinued, repair parts are still available. The body of the device is constucted with ductile iron. The check assemblies are a stainless steel knuckle joint type with a vulcanized rubber clapper plate. A clapper plate retainer tool is required to disassemble the knuckle joint assemblies. The device has bronze seats that are removable but a special seat tool is required.