Not compatible with “Catit” and “Toozey” brand fountains: our fountain filters fit most 1.6-2.5 liter cat fountains! Size: outside diameter 12.6 cm, inside diameter 3.5 cm, thickness 1 cm. Effective filtration: the filter contains activated carbon and ion exchange resins which help to eliminate chlorine, odors and contaminants, effectively filters dirt, encourages your dog and cat to drink more water and promotes pet health and hygiene. EASY TO INSTALL: Rinse the fountain filter 3-5 minutes before use. Keep the filter completely wet to remove carbon dust and keep the flat side up for optimal filtration. Then the installation is complete. 2-3 Week Change: We recommend changing every 2-3 weeks to ensure the best protective filtration for our pets. < p>Scope of delivery: 12 fountain filters, white