0111574 (Watts) | 4 Inch | SS Double Check Detector Assembly Backflow Preventer | Ul/Fm Butterfly Valve Shutoffs | Gallons/Minute MeterThis 4 IN Double Check Detector Backflow Preventer Assembly Prevents The Backflow of Pollutants That Are Objectionable But Not Toxic, From Entering Into The Potable Water Supply. Its Compact Housing Consists of Two Independently Operating Tri Link Check Valves, Two Ul Fm Butterfly Shutoff Valves, And Four Test Cocks. It Has a Gallons Per Minute Meter. It Features a Stainless Steel Housing And Sleeve And is 70 Percent Lighter Than Traditional Designs.