571--CHK-A Fix a failed leaking RV vacuum breaker valve on the black tank flush system line when the black tank flush line system is blocked/faulty and leaking and the RV trailer floor is wet. Exact replacement for cracked and leaking RV vacuum breaker check valve, if your RV vacuum breaker check valve leaked when flushing the black tank, simply replace the RV black tank flush check valve. A perfect vacuum valve for RV black tank flushing. Part of the black tank flush system and installs between the RV inlet connection and the tank flush. The RV black tank flush vacuum breaker helps the RV black tank flush mix with the gray water. RV backflow preventer keeps water source clean and healthy. The black tank anti-siphon/vacuum breaker valve is designed to prevent black tank contents from siphoning back into the RV water supply. Prevent bad water supply contents from backflow and back siphoning. Working water pressure range: 8-125 PSI, Connection type: 1/2 inch NPT male thread on both