PREMIUM QUALITY 1 PIECE PACK: The set includes a 1-piece pack of premium pet fountain replacement filters and a 1-piece pack of replacement pre-filter sponges. They are individually packaged and sealed to maintain high quality. KEEP YOUR PETS HEALTHY: Each filter is made of activated carbon, ion exchange resin and non-woven fabric. They filter out hair, heavy metals and improve the taste of the water, allowing your pet to drink clean and fresh water all day long, which helps increase water intake and reduce the risk of urinary tract infections. In addition, adding a pre-filter sponge around the pump can better filter impurities and extend the life of the pump. Recommendation:To prevent activated carbon dust (which won't harm your pets) from falling into the water, please soak the filter in water for 2 minutes and rinse it thoroughly with running water before use. Regular Filter Replacement: Depending on how often your pet drinks water and the number of pets using the waterer, please replace the filter and sponge every 2 to 3 weeks.