Features: 1.PERFECT MATCH: The cat fountain filter is compatible with most 81 oz or 2.4 liter pet fountains and other fountains of the same size. About 125mm in diameter, 12 filters plus sponge per pack. 2.PREMIUM MATERIAL: Each cat fountain filter is composed of cotton layer, activated carbon and ion exchange resin. Can effectively remove impurities, filter hair, chlorine, heavy metals, odors. 3.KEEP YOUR PET HEALTHY: Cat fountain activated carbon filters get drinking water to help increase water intake, reduce the risk of urinary tract infections, and allow pets to live longer, healthier lives. 4.FREQUENCY OF REPLACEMENT: We recommend replacing pet fountain filters every 2?4 weeks to keep the water clean. Rinse the filter thoroughly with water before use. 5.NOTES AND WARRANTY: To help prevent charcoal dust shedding, provide clean water for cats and dogs by thoroughly flushing the replacement filter of the cat fountain, dog water dispenser with water before use. Specification: Item Type: Pet Fountain Filter Material: Activated Carbon, Resin Compatible: This Cat Fountain Filter is Compatible with for YOUTHINK, for HOMMII, for ISYOUNG, for KOALAD, for HAPPYPAPA, for PEDY PackageList: 12 Piecesx Cat Fountain Filter 12 x Small Sponge Note 1. Please rinse the filter thoroughly with water before use. 2. Change every 2?4 weeks to keep the water clean. 3. Use the fountain to change multiple pets more frequently. 4. Not compatible with for Catit, for MOSPRO brand pet fountain. 5. Please measure the size of your pet waterer before buying a filter, and choose the size of the filter to make sure it fits its size (not bigger or smaller) and can fit it. Install the filter flat side up.