Wide Compatibility- The size of the fountain filter is 4.96 x 4.96 x 0.35 inches and the diameter of the center circle is 1.5 inches. Suitable for most cat fountains of 1.6 / 2 / 2.5 L for cats Please measure your fountain and check before ordering if the filter can be installed in your fountain. Triple Action Filter- Cat Water Fountain Filter use non-woven fabrics, activated carbon and natural resins to effectively purify water, filter harmful substances in water, and provide pure water to people. cats. Easy to Use- Replacement Filters for Cat Dog Just put the raised side down and the flat side up, you can install it easily. Recommendations - Flower Fountain Cat Filters - Please soak in clean water for 2 minutes and rinse before use, replace every 2-4 weeks to ensure the best protective filtration for our pets. Value Filter Set- 8 x Cat Water Fountain Filter, Helps pet increase water intake and reduce the risk of urinary tract infections."