Compatible with? The ec65 filter head for Hayward Perflex EC65, EC65A, EC75, EC75A Extended-Cycle D. Filter Above Ground Spa and Swimming Pool. Better Material? The Hayward filter top is made of strong and stable plastic for enhanced filtration performance and long service life, and the cover fits perfectly in place of the old one. Features? The Perflex filter head comes with an exhaust valve, it is also easy to install and replace. Function? This ec75 filter head is suitable for most above-ground pools and helps to prevent air from getting trapped in the filter.