Water Fountain Filters: Composed of High-quality materials. Effectively to filter hair, heavy metals , keeps water and improve the taste of the water Triple Filtration System: softens hard tap water so that pets can drink clean and water from fountain, Helps pet to increase water consumption and reduce the risk of urinary tract infections. Wide Compatibility: Diameter of hollow circle is about 1.4 inch, Diameter of outer circle is about 5 inch, Compatible with most 84oz/2.5L Round fountain/pet fountains on market. [Keep Your Pet Healthy]Each filter is composed of High-quality materials. They can filter hair, heavy metals, and improve the taste of the water so that pets can drink clean and water all day, which helps to increase water consumption and reduce the risk of urinary tract infections. Also, adding a pre-filter sponge around the pump to better filter impurities and extend pump life. Attention: To prevent the activated carbon dust from shedding into water, please soak for water fountain filters in water for 10 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 size: 10 x 10cm Material: Non-woven fabric + plastic colour: white+black Package Contents: 20 x filter elements 20 x 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.