Apollo 4A205A2F 1" RP4A Reduced Pressure Backflow Preventer. The apollo® model rp4a/rplf4a lead free* & non-lead free series reduced pressure backflow preventers provide maximum protection against backsiphonage or backpressure from substances that are hazardous to the potable water supply. the top accessed modular check valve cartridges provide captured springs, replaceable seats and reversible silicone seat discs. this made in America assembly features ball valves with stainless steel handles and trim as standard and carries the five-year apollo® factory warranty.