571--CHK-A Fix failed leaky rv vacuum breaker valve on black tank flush system line when black tank flush line system was blocked/faulty and leaking and wet rv trailer floor. Exact vacuum breaker check valve rv replacement for cracked and leaking rv check valve,if your rv vacuum breaker check valve was leaking when flushing black tank,just replace rv black tank flush check valve. It's a perfect vacuum valve for rv black tank flush. A part of the black tank flushing system and installs between the freshwater inlet connection and the tank flusher. The vacuum breaker for rv black tank flush,help black tank water for mixing with grey water. RV backflow preventer leaves freshwater source clean and healthy. The black tank anti siphon valve/vacuum breaker is designed to keep what's in the black tank from siphoning back into the rv water supply. Preventing water supply bad contents from backflow and back-siphonage. Work water pressure range: 8-125 PSI, Connection Type: 1/2Inch NPT male threads on both the inlet& outlet. Colour:Black Material:ABS Package Contents: 1 x 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.