12 Packs triple filtration premium water filter compatible with Petlibro PLWF002 71oz/2.1L cat water fountains. Food grade activated carbon water filter removes impurities, bad tastes and odors from water, making the water fresh and keep your cat hydrated. Ion exchange resins remove harmful contaminants from liquids, replacing them with beneficial, desired ions. Nispira branded filters contain 50% more carbon than generic brands for better and longer-lasting filtration. Suggest to change every 2-4 weeks to maintain water freshness. 100% customer satisfaction guaranteed. Quality meets or exceeds leading national brand