[Compatibility] ONLY Compatible with Water Fountain PLWF105 / PLWF115 / PLWF005. If any doubt, please check product dimensions. [Compatible Pet Filter] Length is about 3.75 inch. Width is about 2.30 inch. Thickness is about 0.43 inch. [Premium Quality Filters] Triple Filtration System: Composed of a cotton layer, activated carbon and an ion exchange resin. Effectively to filter hair, heavy metals, keeps water fresh and improve the taste of the water. [Frequency Of Replacement] To prevent the activated carbon dust from shedding into water, please soak the cat fountain filter in water for 5 minutes then rinse thoroughly under running water before using. 1 to 2 weeks in summer and 2 to 4 weeks in winter. If multiple cats are using the fountain, more frequent replacement will be necessary. [Premium 12 Pack Pet Fountain Filters] 12-pack of premium pet fountain replacement filters and 10 Pack of pre-filter sponges packaged and sealed to maintain high quality. Enough supply for 3 to 12 months of use. Replace the pre-filter sponge every 2-4 weeks. [Friendly Customer Service] Please feel free to contact us if you have any questions about our products, we'd like to help you!