VistaCheck™ Dual Check Valve Backflow Preventer (1/4") VistaCheck™ Dual Check Valve Backflow Preventer (1/4") CVVC250-A VistaCheck™ is a CSA-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 x Category Dealer PartnersSales RepresentativeStrategic MarketsSchools RepresentativeAccutron™ Equipment Sales Zip Code Find RepresentativeReset Select a category, input a zip code and click on Find Representative, or explore the complete list here.