Pleatco PRB8.5-M Replacement Cartridge for Rainbow Chloro (MICROBAN), 1 Cartridge Replacement cartridge for rainbow chloro 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 C-2303 and filbur FC-2324; made in usa; microban inhibits the growth of stain and odor causing microbes like bacteria and algea Measures 2-7/8-inches in diameter by 17-1/16-inches in length and 2-1/8-inches of top and bottom hole diameters