Pleatco PSG13.5-M Replacement Cartridge for Saratoga Spas (MICROBAN), 1 Cartridge Replacement cartridge for saratoga spas 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 FC-0185; made in usa; microban inhibits the growth of stain and odor causing microbes like bacteria and algea Measures 4-3/4-inches in diameter by 5-15/16-inches in length and 1-9/10-inches of bottom hole diameter