The 2-1/2 in 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 stainless steel snap-in retainers (2-1/2 in to 6 in) or stainless steel studs & nuts (8 in to 12 in). Access to the check valves shall be by an Apollo™ quick-connect stainless steel coupling (2-1/2 in to 6 in) or grooved couplings (8 in to 12 in). The bodies shall be domestic stainless steel in 2-1/2 in to 8 in sizes and FDA epoxy coated ductile iron in 10 in & 12 in sizes. The lead free Apollo™ domestic ball valve test cocks shall have stainless steel 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.