【Compatibility】: The replacement carbon filters for cat fountains are compatible with 1/2 gallon, 1 gallon, 2 gallon, Butterfly, Avalon, Pagoda, Seascape, Sedona, Seaside and Creekside pet fountains; 【Three-layer Filtration】: This replacement filter consists of a layer of cotton, activated carbon. It removes hair, debris, odors and other impurities so that the water always tastes fresh and clean; 【Pre-filter sponges】: The sponge can prevent debris from clogging and damaging the pump, thus extending its service life; 【Change the filter regularly】: Please soak the filter in water for 5 minutes before use and rinse it thoroughly under running water. Replace the filter of the cat water dispenser once every 4 weeks in summer and once every 4 to 6 weeks in winter to ensure clean drinking water. Changes are more frequent if several animals use the fountain;