Promote healthy hydration for your cat with CATLINK Water Filter as it soften the water while the water passes thru the five filtering levels and eliminates hair, debris, calcium and magnesium ions that may cause sickness in cats. Features Designed with multiple filtration processes for soft, healthy, clean, and safe drinking water. Suitable and ideal filter for CATLINK PURE Smart Pet Water Fountain. Removes calcium and magnesium ions, and stops scale precipitation that causes water to be "hard". A cotton filter is the first stage that removes floating hair, impurities and dirt from the water. Activated Charcoal, the second stage of filtering, removes organic substances, iron oxide, and residual chlorine that can cause sickness in cats. The calcium Sulfite Filter is the third stage that eliminates residual chlorine and colloids. KDF, a high-end purification material, serves as the fourth filter stage, removing chlorine, heavy metals, and acid ions. Resin as the last stage of filtering makes the water soft by removing calcium and magnesium ions. Recommended for all breeds and life stages of cats, especially those with kidney disease and pregnant cats.