compatibility -This pet water fountain filter is suitable for the 3 litre catit flower cat water fountain Please make sure these cat fountain filter replacement size is compatible with your cat fountain before purchasewill not fit non catit (16 litre) fountains Dimensions: outer diameter 140mm 55inch Better Filtration -This cat water fountain filter is composed of a layer of high qunlitty cotton+Ion exchange resin + activated carbon Help to remove dirt absorb heavy metals eliminate odors in the water with our cat fountain filters keep water tasting fresh and clean all the time for your pets Protect the Health of Pets-Using this pet water fountain filter can help to provide clean and fresh water for your pet and help reduce the risk of urinary tract infection it is very important for the health of pets Suggestion-Soak the cat filters for water fountain for 20 seconds before use To maintain the filtering effec recommended to replace the cat fountain filters every 2-4 weeksAny problem or help if you need please tell us by email and we are here to help 6 Pack Individual Packaged cat Fountain Filter-This product contains 6 pieces of cat fountain filter replacement each of this pet water fountain filter is individually packaged which effectively ensures the tightness of each piece of cat water fountain filter