Perfect Compatible: cat water fountain filters are compatible with 67 oz/2L, 95 oz/2.8L or 135 oz/4L automatic cat pet water fountains. The size of filter is 3.9 x 3.9 x 0.4Inch, the size of sponge is 1.5 x 1.1 x 1.0Inch.Note: Not compatible with 84 oz/2.5 L pet fountain. Please check your fountain model before purchasing. 20 Filters & 20 Sponges: premium 40 pack cat fountain filters set includes 20 pcs replacement filters and 20 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 square 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 new 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 20+20 pack combination is can replace them regularly and enough for 10-12 months usage. Color:White & Black Material:plastic Package Contents: 20 * filter element 20 * pre 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.