[Quadruple Cycle Filtration System] The quadruple cycle filtration system is composed of biochemical cotton, microporous filter cotton, coconut shell activated carbon and ion exchange resin.[More Professional Filtering] The cat water fountain filter can effectively filter impurities, purify and soften the water quality, and prevent the water pump from clogging.[Keep Your Pet Healthy] The cat fountain filter replacement can provide your pet with healthy and clean water and reduce the risk of illness. 4-piece pet fountain filter replacement, individually packaged and sealed to maintain high quality.[Perfect Match] The diameter of the filter of the cat drinking fountain is 4.13 inch. The filter for cat fountain is compatible with for Biubiucat's pet water dispenser and is easy to use.[Recommendations] Please soak the filter for ten minutes before use, and clean it at least once a week. Depending on your pet's drinking frequency and the number of pets using the fountain, change the filter every 2-4 weeks.Material:plasticcolour:white+bluePackage Contents:4 * Fountain FiltersOnly the above package content, other products are not included.Note: Light 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.