4 PiecesReplacement cat fountain filters are individually wrapped and sealed to maintain high quality, our cat fountain filters can be matched with a wide range of pet water fountains. Large quantityPremium quality cat water fountain filters with more coconut shell carbon than most pet fountain filters on the market to achieve better purification performance. Purification principle Physical purification, without side effects. Charcoal is made from high quality carbon, which is activated by a physical method, refined and processed. HealthyKeep your pet healthy, the charcoal filter helps isolate hair, absorb odor and soften water, get water taste to keep cat away from urinary tract infections. Unique DesignCompared with conventional filters, this cat fountain filter replacement could make longer lasting filtration and requires less frequent water changes.