Designed to prevent high hazard backsiphonage backflow and low lead backpressure (10 ft or less) from contaminating the potable water supply. It is ideally suited to prevent backflow associated with hose connections and may be screwed directly to the sill cock, yard hydrant, or wall hydrant. Typical installations include service sinks, chemical dispensers, sill cocks, and frost proof hydrants. Features include 2 independently operating rubber and stainless steel check valves with an atmospheric vent located between the check valves. In the event of fouling of downstream check valve, leakage would be vented to atmosphere, thereby, providing a visual indication of failure. The integrity of the check valves can also be verified by performing the field test procedure included with the valve. Manufactured to include no more than 0.25% weighted average lead content on wetted surfaces.