The 3" Watts Series 709 Double Check Valve Assembly began production in 1973 and is still currently being produced. It was available in bronze or epoxy coated cast iron bodied. Usually blue in color. Two cover design. The 709 uses self contained bronze check assemblies. The seats are bronze and replacable. In 2010, A lead free version was introduced, designated with a "LF" prefix. In 2013, the regular leaded devices were discontinued, Lead Free version is the only 709 available. No special tools are required for servicing