CompatibilityThe cat fountain filter replacement is only compatible with 2.5L/84oz Dockstream cat water fountain PLWF005/PLWF115/PLWF105.ountain Filter. Triple Filtration SystemThe pet fountain filter is composed of a cotton layer, activated carbon and an ion exchange resin. Effectively to filter hair and residue, absorb odors, soften water keeps water fresh and improve the taste of the water. So that pets can drink clean and fresh water all day. Value Filter SetYou will receive 12 pack cat fountain filter replacement, which are separately packaged and sealed to maintain high quality. Enough for daily use and replacement of your pet water fountain. TipsBefore replacing the filter, please soak the filter in water for 5-10 minutes and then rinse for 30 seconds, which can prevent carbon dust from shedding into water. ReplaceTo maintain the filtering effect, suggest replacing filter and sponge every 2-4 weeks. If you have multiple pets, please change the filter and clean the fountain more often.