Hayward Perflex DE Extended Cycle Filters provide crystal clear, sparkling water at an economical price. Proven over many years, Perflex has set the standard in swimming pool filtration by incorporating a patented Flex-Tube design in combination with DE filter powder, the most efficient dirt remover known for pool filtration. The result is superior water clarity, extended filter cleaning cycles and no backwashing required. Exclusive bump handle activates the Flex-Tubes causing them to instantly purge themselves of dirt and powder. Combination diffuser and lower mixing chamber are specifically designed to produce a uniform coating of DE on the Flex Tubes. Pressure gauge and built-in check valve included.