The Hayward W3S310T2 30 inch Pro Series Pool and Spa Sand Filter is built with a top diffuser which evenly distributes water over the sand providing the best filtration possible while the self cleaning 360 degree laterals provide an efficient flow of clean water to your pool and more thorough backwashes. The W3S310T2 includes an easy to use multiple position valve which allows for efficient and simple operation. The filter operates for shorter periods of time with it's full-flow technology ultimately saving you money. Built to last, Pro Series Sand Filters are molded with durable, corrosion-proof reinforced thermoplastic.