KEEP YOUR PET HEALTHY: Every filter for cat fountain is composed of a cotton layer, activated carbon, and an ion exchange resin. It can effectively remove impurities, filter hair, chlorine, heavy metals, and odors. NOTE : To help prevent the charcoal dust from shedding, please rinse the replacement filters for cat fountain/dog water dispenser with water thoroughly before use, providing the clean water for cats and dogs. FILTER WORKS LIKE A CHARM: Fountain filter features the strongest purification that a common one cannot to, which just catches the larger, but it can catches everything, let alone to filter out dust, hair and heavy metals. Water purified by filter has an improved taste of being cleaner and fresher. MATCH: Cat Water Fountain Filter most 102oz/3L Round Pet Fountain FREQUENCY OF REPLACEMENT: We suggest to replace the pet fountain filter 2-4 weeks to keep the water fresh and clean Material: pp cotton activated carbon resin colour: Black Package Contents: 20 x Pet Fountain Filter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.