Compatible with Catit Water Fountains Only: The diameter of these Catit filters replacement is 5.5”, so they are only compatible with Catit Flower Fountain，Catit Design Senses Fountain and Catit Senses 2.0. NOT fit for other brands fountains. Provide Healthy Drinking Water for your Pets: These filters for Catit water fountain are made of cotton mesh, ion exchange resin, and activated carbon.Triple Filtration purified filtering out hair, sediment, and debris.Removing water smell,making water more clean and fresh. Replace the filters monthly: F