The Rheem Check Valve Kit (with O-Ring), part number RTG20319AS, is a crucial component designed for Rheem tankless gas water heater systems. This specialized kit prevents backflow of water, ensuring smooth and efficient operation of the unit. Engineered with precision and durability, it includes an O-ring for secure installation. Specifically tailored for Rheem units, this check valve kit guarantees optimal functionality, providing reliable and consistent hot water supply for residential and commercial applications.