【Maoquan filter】The cotton layer, activated carbon and ion exchange resin form a three-layer filter system. They can filter hair, particles, heavy metals, improve the taste of water, and allow pets to drink clean and fresh water from Cat Springs. 【Good suitability】 Compatible with 84oz/2.5L Round Cat Fountain / Pet Fountain as pictured. 【Recommendation】Please soak the filter in water for 2 minutes before use, then rinse thoroughly with running water and replace filter every 2-4 weeks. < p>【Individually Packaged】Cat fountain replacement filters are individually packaged and sealed to maintain high quality.