Pleatco PRB25SF-PAIR Replacement Cartridge for Dynamic Series IV, Model DSF, DFML-25C, Waterway Models, 2 Count Replacement cartridge for dynamic series IV, DSF, dfml-25c, waterway models 50 Percent open ABS free flow cores maximize water flow through reemay filter media Antimicrobial end caps resist chlorine degradation and provide support to filter material for a longer life span Replaces unicel and filbur; made in usa; microban inhibits the growth of stain and odor causing microbes like bacteria and algea Measures 5-inches in diameter by 6-5/8-inches in length and 2-1/8-inches of top and bottom hole diameters