Replacement filter for cat fountain. Keep your cat’s drinking water fresh, clean and safe. Help you take care of your cat’s health. Most filters on the market are made from activated carbon. But these filters are made from high quality activated carbon, resin and cotton mesh. Water is deeply purified and safer. Features: Compatible with YOUTHINK, HOMMI, ISYOUNG, KOALAD, HAPPYPAPA, PEDY and others of the same size. Size: 5 inches (outer diameter), 1.5 inches (inner diameter). Dual Action Filters: Resin and Activated Carbon. The resin can soften the water and reduce the risk of lithiasis. Activated carbon can adsorb impurities and odors, keep water fresh and clean. Water quality can be removed by the three 3 kinds of filtration. The outer cotton layer on each filter captures hair and debris. Three stages of filtration can ensure water quality and enhance the taste of fresh water for your cats. Rinse the filter thoroughly with water before using, easy to mount on the pet water fountain.