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. Specifications: 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 Package List 12 Pieces x Cat Fountain Filter 12 x Small Sponge