The 2-1/2 to 12 in Backflow Preventer shall be an Apollo™ Model DCLF 4A Lead Free Double Check Valve. The assembly shall be manufactured in America and carry a 5-year Apollo™ factory warranty. The TriForce™ center stem guided check valves shall feature reversible silicone rubber seat discs. The check valves shall be held in place by SS snap-in retainers (2-1/2 to 6 in) or SS studs & nuts (8 to 12 in). Access to the check valves shall be by an Apollo™ quick-connect SS coupling (2-1/2 to 6 in) or grooved couplings (8 to 12 in). The bodies shall be domestic SS in 2-1/2 to 8 in sizes and FDA epoxy coated ductile iron in 10 and 12 in sizes. The Lead Free Apollo™ domestic ball valve test cocks shall have SS handles. The assembly shall prevent contamination of the potable water supply due to back-siphonage or backpressure from substances that are non-health hazards. The pressure drop across the assembly shall be documented by an independent laboratory.