Apollo 4AY104A2FB 3/4" Bronze Double Check Valve - This Apollo® Double Check Valve prevents contamination of the potable water supply due to back-siphonage or backpressure from substances that are objectionable to the potable water supply, but non-health hazards. The modular check valve cartridge provides captured springs, replaceable seats, and reversible silicone seat discs. This Made in America assembly with stainless steel handles and nuts carries the five-year Apollo® factory warranty.