Pleatco PWK30-M Replacement Cartridge for Watkins Hot Spring Spas (MICROBAN)， 1 Cartridge<div style="text-align: left;"><strong>[Product Information]</strong><br><ul><li>Replacement cartridge for watkins hot spring spas</li><li>50 Percent open ABS free flow cores maximize water flow through reemay filter media</li><li>Antimicrobial end caps resist chlorine degradation and provide support to filter material for a longer life span</li><li>Replaces unicel C-6430 and filbur FC-3915; made in usa; microban inhibits the growth of stain and odor causing microbes like bacteria and algea</li><li>Measures 5-7/8-inches in diameter by 10-1/2-inches in length and 1-15/16-inches of top and bottom hole diameters</li></ul></div><img src="http://ecx.images-amazon.com/images/I/51P1xHT4QkL.jpg" noproxy>