Wide Compatibility: This cat water fountain filter is suitable for drinking fountains. Dual Action Filter: With the dual action water softener filter for lon Exchange resin and activated carbon, it can effectively filter dirt. Design: Unique design that removes impurities and provides only fresh water for your cat. Easy to Use: Rinse the filter with water before use and replace it every 2-4 weeks to keep the water fresh. Healthier Drinking Water: Reverse osmosis of the pet water dispenser filter, layer by layer to block impurities in the water, remove heavy metal elements, mitigate water quality, make the water softer, and effectively prevent pet urinary system diseases.