The Zurn Wilkins 475ST Stainless Steel n-Pattern Reduced Pressure Principle Assembly is ideal for new or direct drop-in replacement, delivering convenience without compromise. Compact and reliable, this reduced pressure principle assembly withstands the corrosive effects of water and protects against both backsiphonage and backpressure of polluted water into the potable water supply. The 475ST model is approved for applications requiring flow vertical up and vertical down. The patented AR spool offers flexibility in replacing older models with different lay lengths and maintains agency approvals when installed by the factory.