Perfect Match - cat water fountain filters are compatible with 81oz/2.4L round automatic cat pet water fountains. Filter outer dia is 5Inch, inner circle dia is 1.4Inch, sponge size is 2.5 x 1.2 x 1.1Inch. Note:Not compatible with 106 oz/3 L pet fountain. Please check your fountain model before purchasing. 8 Filters & 4 Sponges: premium 12 pack cat fountain filters set includes 8 pcs replacement filters and 4 pcs pre-filter sponges. Pre-filters foam can effectively filters out food debris and pet hair, ensures fresh and clean drinking water for cat dog, keep your pet healthy. The sponges also can extends the life of the pump. All For Your Pet's Health: pet fountain filters are composed of cotton layers, coconut shell activated carbon, ion exchange resin. Every drop of water is filtered through Three-Layer filtration to remove impurities and provide oxygen-enriched and better-tasting water. Let your lovely pets can drink clean and fresh water all day, which helps to increase water consumption. Easy to Install & Clean: cat water filters replacement is easy to remove and apply a one, effectively reduces cleaning frequency. To provide a better drinking experience for your pet, please soak the filter in water for at least 3 minutes, then rinse thoroughly under running water before using, keeps cat water fresh for a longer period of time. Regularly Replacement: Recommend replacing the filter every 2-4 weeks, depending on the number of cats in your home, and meanwhile clean the fountain and the pump to extend service life. The 8+4 pack combination is can replace them regularly and enough for 4-6 months usage. Color:As Shown Material:Non-Woven Fabric + Resin Package Contents: 8 * filter element 4 * sponge 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.