Pleatco PWW50L-M Antimicrobial Replacement Cartridge For Waterway Teleweir 50 Replacement cartridge for waterway teleweir 50-square-foot filter 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 4CH-949 and filbur FC-0172; made in USA; microban inhibits the growth of stain and odor causing microbes like bacteria and algea