VistaCheck™ Dual Check Valve Backflow Preventer (1/4") VistaCheck™ Dual Check Valve Backflow Preventer (1/4") Sign in to save to your list CVVC250-A VistaCheck™ is a QAI-certified dual check valve backflow prevention device that can eliminate the need for expensive reduced pressure zone (RPZ) valves, vacuum breakers, and air gaps. Where to Buy Ask a specialist