This 3/8" dual check valve backflow preventer with atmospheric port and strainer for carbonated beverage machines prevents the reverse flow of polluted water, such as carbon dioxide gas and carbonated water, from entering into the potable water supply due to backpressure backflow. It is designed for continuous or intermittent pressure applications and ideal for use on post-mix carbonated beverage equipment and dispensing equipment for tea and coffee. This valve consists of stainless steel body construction, male NPT end connections , internal rubber components and an atmospheric vent."cludes an atmospheric port provides visual indication of failure of the second check. Male NPT end connections