Effective backflow prevention: This 12.7 cm check valve uses a spring-loaded flap to reliably block reverse flow, helping your sump pump operate smoothly without interruptions. Transparent body for easy monitoring: The clear housing lets you easily observe valve movement inside, so you can verify performance at a glance. Durable materials: Constructed from robust ABS and metal components, built for long-lasting reliability in plumbing systems. Compatibility and sizing: Refer to the size chart to confirm a proper fit with your home piping for an optimal seal and performance. Practical use scenarios: - Basement sump pump discharge line to prevent backflow during heavy rain or sewer backup - Crawl space drainage lines where backflow risk exists - Laundry or utility sink drains to guard against sewer backflow into the home