2L water reservoir Easy to clean and maintain Replaceable Foam/Carbon Filter: collects food, hair, and debris; also helps to reduce bad tastes, odors, and absorbs impurities present in tap water Re-circulating water flow: cools and aerates the water, eliminates stagnant water Large water-to-surface area adds oxygen to water: for fresher, tastier water Suitable for cats and small dogs Encorage cat to drink more water Replacement foam/carbon filters (Art. # 50057) also available (sold separately).