WIDE COMPATIBILITY: This cat fountain filter is suitable for water fountains. Dual-action filter: With the dual-action water softener filter for resin replacement and activated carbon, it can effectively filter dirt. Design: Unique design that removes impurities and provides your cat with only fresh water. Easy to use: Rinse the filter with water before use and replace it every 2 to 4 weeks to keep the water fresh. Drinking water is healthier: Pet reverse osmosis filter water dispenser, layer by layer to block impurities in the water, remove heavy metal elements, moderate water quality, make the water softer, and effectively prevent urinary tract diseases in pets.