Product Description Triple Filtration for Healthy Water Protection 1: High-Intensity Cotton When it sits on the ground, hair, dust, and other small impurities can easily fall into the well. Thanks to the high-intensity cotton, our well filter can effectively filter out hair, dirt, and sediment. Protection 2: Coconut Activated Carbon Made from natural coconut shells, it removes residual chlorine and other infectious microorganisms. Purifies drinking water and further improves its taste, which arouses the interest of our pets. Protection 3: Ion Exchange Resin Drinking untreated tap water can accumulate calcium and magnesium ions and cause stone problems in our pets. English: Ion exchange resin helps extract heavy metal ions, softens tap water, and protects our pets' urinary health. Please measure the dimensions before purchasing! Outer diameter 125mm Inner diameter 37mm Generally suitable for 2.0-2.5L cat fountains, e.g., Aerb, DAYPET, Parner, Toozey, and especially PewinGo cat