Just a single one of these pocket-sized PIXI Fountain Filters will help keep your cats drinking water tasty fresh for a whole month, and even reduces the risk of urinary tract disease. Catit PIXI Fountain Filters consist of three components that purify your cats drinking wate: The cotton mesh, in the filters outer layer, removes hair, sediment, and debris, such as bits of food. Active carbon helps remove odors and impurities. Ion exchange resin softens tap water by filtering out excess calcium and magnesium. When present in large amounts, these minerals can pile up in your cats lower urinary tract and may lead to urinary tract disease.