Multi Filtration Circulating Water System: 2.0L Duoai pet water fountain comes with a filter element. It has a filtering function to provide pets with cleaner water to prevent urinary stone diseases Ultra-Quiet Intelligent Pump: The pump is ultra-quiet (measured below 30dB which gives your pets 100% sweet sleep. Duoai cat water fountain comes with auto off function at a low water level Filter Element and Sponge: The filter in the dog water despenser is able to effectively remove odors impurities and soften water to protect pets healthy. There is a replaceable sponge to the pump which could filter smaller impurities.Please search B097QXG83G for the replacement filters.Please search B097QWXJXW for the replacement Sponge BPA free Quality Material: The pet fountain is made of food-grade material which is BPA free. Duoai cat water fountain use more durable and steady material that meets pets health standards Adjustable Stream and Simple Operation: The water flow design attract pets to drink more water. The water valve able to allows you to customize water flow for your pet. This cat water despenser is easy to install and designed to disassemble for cleaning