Pioneer Pet Vortex Drinking Fountain features a lower profile that is ideal for cats or small dogs. The vortex action helps contain splashing and pulls debris away from drinking area. The replaceable charcoal filter helps keep water fresh and clean. In addition, it contains an auto shut-off pump when water level gets low. The fountain comes with one filter for initial setup. It is recommended to change filter every 2 to 4 weeks depending on usage.