Wide Compatibility: Our fountain filter fits most 1.6-2.5 liter cat fountains! Dimensions: outer diameter 125 mm, inner diameter 33 mm, thickness 5 mm. Effective Filtration: The filter includes activated carbon and ion exchange resin, which can help remove chlorine, odors and contaminants, effectively filtering dirt, encouraging your dogs and cats to drink more and promoting the health and hygiene of pets. 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 to ensure the best filtration. Then the installation is complete. 2-3 Week Change: We suggest changing every 2-3 weeks to ensure the best protective filtration for our animals. Tips: Make sure the filter size is suitable for your fountain before purchasing and clean the filter thoroughly with water before use. Please feel free to contact us if you have any problem with our product, we will do our best to help! Why choose our cat water