Hayward W3S210T 20" Pro Series Sand Filter. Hayward ProSeries top mount sand filters utilize a precision engineered umbrella fold self cleaning lateral system to provide efficient flow and evenly distributed water for totally balanced backwashing and long lasting performance. The ProSeries filter features an integral top diffuser that evenly distributes unfiltered water over the sand media bed, this allows the greatest filtration possible from every square inch of sand. Features:High-performance top-mount sand filter for above-ground pools, small in-ground pools, and aquariumsCorrosion-proof filter tank molded of color-fast material for long-lasting; 7-position vari-flo valve provides maximum flow at lower pressure dropDurable; large pressure sand/water drain for rapid winterizing or servicing; round base included; all-weather performanceFlange clamp design allows 360-degree rotation for easy installationIntegral top diffuser ensures even distribution of water over the entire sand bed for maximum use of the filtration area