The Hayward Perflex Extended-Cycle Diatomaceous Earth Pool Filter cleans pools quickly, removing particles as small as one micron the first time through. Its patented Flex-Tube design increases time between cleaning cycles by efficiently re-utilizing the diatomaceous earth filter powder through multiple uses. Plus, Perflex cleans without backwashing, saving hundreds of gallons of treated pool water. Designed for in-ground pools of all types and sizes, Perflex provides exceptional value as a replacement filter or for new pool installations.