Series 773 Double Check Valve Assemblies were produced from 1998 - 1999. Only available in sizes 4 - 6", the 773's internal parts are similar to a 709 with the body reconfigured for "N" shaped and "Z" shaped installations. The body was made of epoxy coated cast iron. The 773 does have self contained check valves and replaceable bronze seats. No special tools are required for service.