Dogness Smart Fountain Plus holds up to 3.2 liters (almost 1 gallon) and the fountain-style continuously flows the water to aerate and reduce stagnation, while the built-in triple-layer filtration system ensures the water is fresh and odor-free. 【CONTINUOUS FLOW】: the water flows upward, just like a drinking fountain for humans, but for dogs and cats. The continuous flow keeps the water fresh, oxygenates, and eliminates stagnation. 【CAPACITY】: 3.2 Liter capacity with a visible water level on the side that's easy to see. 【WATER LEVEL SENSORS】: equipped with a sensor to monitor the water level, when low the LED light color changes from Blue to Red as a visual reminder to refill soon. 【DRY RUN PROTECTION】: The pump automatically shuts off if and when the tank is empty to prevent damage to the pump. 【THREE-LAYER FILTRATION】: includes one carbon nano filter, designed to last up to 6 weeks. ULTRA-Q【QUIET】: equipped with a special muffler to significantly reduce water noise. 【SIZE】: 7.79" H x 9.13" W. 1.98 lbs. POWER: USB power adapter with a 5.5' ft long cable, not battery operated.