Replacement filter for cat fountain. Keep your cat’s drinking water is fresh, clean and safe. Helping you to take care of your cat’s health. Most of the filters in the market are made of activated carbon. But this filters are made of high quality activated carbon, resin and cotton mesh. The water is deeply purified and safer. Features: Value pack of 4 filters. Dual-action filters: Resin and active carbon. Resin can soften water and reduce the chance of lithiasis. Activated carbon can adsorb impurities and odor, keep the water fresh and clean. Water quality can be removed by the three 3 types of filtration. The external cotton layer on each filter captures hair and debris. Three steps of filtration can assure the quality of the water and enhance the taste of fresh water for your cats. Rinse the filter with water thoroughly before using, easy to mount it on pet water fountain. In order to ensure the water clean, the filter should be replaced in time, please replace them within 2 to 4