[Perfect compatibility] Compatible with the HAPUP water fountain for cats and dogs. Encourage Your Pet To Drink More Water And Stay Healthy. [Triple Filtration System] Each cat water fountain filter is made of porous filter cotton with high density cotton layer, activated carbon of high quality and an ion exchange resin. Cotton layer: filters hair, sediment and debris. Activated carbon: eliminates bacteria and chlorine odors. Ion exchange resin: softens tap water and helps prevent urinary tract diseases. It can keep the cat's drinking water clean and fresh. [Safe Premium Quality]Replacement cat water fountain filters are made of high quality material, non-toxic, visible, easy to clean. use and clean. Plus, black and white design makes it easy to know when to clean and change filters. The filter provides cleaner water for your pet and reduces the risk of disease. [Replacement Cycle] To help prevent charcoal dust from escaping, please rinse the fountain filter thoroughly cat under running water before use, and soak it for ten minutes (a little activated carbon powder is normal), providing clean water for cats and dogs. Clean the HAPUP Cat Fountain Filter weekly. We recommend replacing the filter every four weeks to keep the water clean. [Bargain and Friendly Service] It's a bargain to have these 6 pet fountain filters , which can ensure you long-term use.