Product description Size: outer diameter 12.7cm, inner diameter 4cm, thickness 1cm color: White Material: Resin Package content: 4pcs/8pcs filter cotton 1.FULLY COMPATIBLE: This flower fountain filter is fully compatible with pet water fountain. 2.IMPROVE WATER: The water quality can be reduced by the three 3 types of filtration. The outer polyester layer on each filter catches hair and dirt. Three steps of filtration can ensure the quality of water and improve the taste of fresh water for your cats. 3.EASY TO USE: Rinse the filter thoroughly with water before use, so it can be easily mounted to the fountain 4.KEEP YOUR PET HEALTHYEach filter is composed of a cotton layer, activated carbon, and an ion exchange resin. They can filter hair, heavy metals, and improve the taste of the water so that pets can drink clean and fresh water all day, which helps to increase water consumption and reduce the risk of urinary tract infections. 5.CAT WATER FILTER FREQUENCY OF REPLACEMENT: Its recommended to replace the pet fountain filter replacement 2-4 weeks to keep the water quality. If multiple pets are using the fountain, more frequent replacement carbon filters for pet fountain will be necessary.