Pleatco PGS25P4-M Replacement Cartridge for After Hours Spas, Nemco Spas, Threaded 25-Square-Foot Top Load (MICROBAN), 1 Cartridge Replacement cartridge for after hours spas, nemco spas, threaded 25-square-foot top load 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-4CH-24 and filbur FC-0131; made in usa; microban inhibits the growth of stain and odor causing microbes like bacteria and algea Measures 4-5/8-inches in diameter by 9-3/4-inches in length and 1-1/2-inches of bottom hole diameter