3/6/9 Pack Cat Water Fountain Filters Compatible with Catit Fountains, Petilog Carbon and Ion Exchange Resin Pet Fountain Filter Replacmence (9)Applicable water fountain: This cat water fountain filter is compatible with Catit round cat water dispenser. Package: The package contains 9 cat fountain filters. Suggestions for use: To keep the drinking water fresh and hygienic, it is recommended to replace the pet water fountain filters every 2 4 weeks, depending on the number of cats in your home. Before using the pet fountain filter replacement, rinse them thoroughly under running water and then