The FEBCO T683039 is a 3/4" LF850 Double Check Valve Backflow Preventer Assembly, Quarter Turn. The FEBCO Series LF850 Lead Free* Double Check Valve Assemblies are designed to prevent the backflow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure. Features a lead free body construction, NPT end connections, top mounted test cocks, and quarter turn ball valve shutoffs.