0122711 (Watts) | 4 Inch | Lead Free Double Check Detector Backflow Preventer Assembly | Osy Shutoff Valves | Cubic Feet MeterThis 4 Inch Lead Free Testable 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 Shutoff Valves, And Four Test Cocks. It Features a Stainless Steel Housing And Sleeve And is 70 Percent Lighter Than Traditional Designs. It is Designed For Non Health