Pleatco PWW10PAIR Replacement Cartridge for Waterway Skim Filter 10, 1 Pair Replacement cartridge for waterway skim filter 10 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-4310 and filbur FC-3077; made in usa; microban inhibits the growth of stain and odor causing microbes like bacteria and algae Measures 4-1/4-inches in diameter by 4-inches in length and 2-1/16-inches of top and bottom hole diameters