Zurn 475 Series Reduced Pressure Principle Assemblies are designed for installation on potable water lines to protect against both backsiphonage and backpressure of contaminated water into the potable water supply. Assembly shall provide protection where a potential health hazard exists. The Model 475 is for applications requiring vertical flow up and vertical flow down. The Model 475V is for applications requiring vertical flow up. Ideal for use where lead-free* valves are required.