PetsN'all Waterfall Filtration Circulating Pet Drinker High capacity (4L) circulating fountain provides a fresh supply of clean, filtered water all day long Circulating water flow aerates and oxygenates pet drinking water for fresh taste Multi-height drinking levels makes it ideal for finicky cats and dogs, older pets and multi-pet households Encourages cats and dogs to drink more water for good hydration and health Comes with polymer-carbon filter, which absorbs odor, chlorine, organic matter and other impurities (For replacement, see PetsN'all Waterfall Replacement Filters)