These valves prevent backflow in plumbing systems. Made from PVC, they are resistant to corrosion and chemicals, making them suitable for a wide range of applications, including water and wastewater systems. CMI’S REV Compact Check Valves are manufactured from high quality materials to ensure high reliability and low maintenance. They are suitable for 2” or 1.5” applications. The Check valve with sight glass can be replaced (slides out) without removing end caps. The valve assembly has a clear connection for easy viewing of proper flow.