H2Flow Flow Meter Check Valve [FlowVis, Jandy Praher Retrofit] (FVJ R 15) safety A roller brush is useful A roller brush is useful because it helps the cleaner maintain contact with the pool surface while assisting with scrubbing and debris pickup during operation The WC62021 is a practical maintenance part when a compatible Waterco Trimline tank needs fresh lid sealing support for better everyday service performance The H2Flow FlowVis flow meter and check valve is designed for compatible Jandy and Praher retrofit plumbing applications where both flow monitoring and check valve protection are needed This replacement is especially useful when the original assembly is inaccurate