Keep Your Pets Healthy: Our cat water fountain filters offer your furry friends fresh and clean running water. Encouraging them to drink more and keeping the body's hydration, effectively to prevent urinary tract infections. Four-layer Filtration System: This cat water fountain filter replacement contains activated carbon, which together with the non-woven fabric form a four layer circulating filtration system. This effectively filters pet hair, food residue, absorbs odors, and softens the water, providing your pet with fresh, healthy drinking water. 3+3 Pack Filters: Package incudes 3 pack of cat water fountain replacement filters and 3 replacement pre-filter sponges, well packed into one box. To the water fresh and hygienic, please replace the pet water fountain filters and clean the water fountain every 2-3 weeks. Good Compatibility: The pet water fountain filter compatible with 4L/135oz and 3.2L/108oz Stainless steel Pet Fountain. Or any pet fountain filter case with the size match. (Filter size: 3.7 x 1.6 x 0.7 inch | Sponge size: 2.4 x 1.1 x 0.39 inch). Using Tips: Please soak the carbon fountain filters for 5 minutes and rinse it thoroughly before use to prevent the activated carbon dust shedding into the water. Colour:As Shown Material:Composite Materials Package Contents: 3 * hepa filter 3 * filter cotton 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.