RV Vacuum Breaker Check Valve: fit for Model 571 Check valve,This check valve is a part of the black tank flushing system and installed between the freshwater inlet and the tank flusher. Designed to prevent backflow and back-siphonage, keeping your freshwater source clean and healthy. Easy Installation: With 1/2Inch NPT male threads on both the inlet and outlet, this vacuum breaker check valve is simple to install in your RV's black tank flushing system, and must be installed a minimum of 6 inches above the highest point of any item connected to the waste tank where the flusher is installed. Versatile Application: Suitable for various RV models, campers, travel trailers, and motor homes, the 571-VAC-CHK-A RV tank flush one way check valve is a reliable replacement for cracked or leaking check valves, ensuring efficient water flow. Please note:the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Colour:As Shown Material:brass Package Contents: 1 * RV Vacuum Breaker Check Valve Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.