Visibly cool mist and style. The Homedics ultrasonic humidifier disperses a cool mist you can see with 360-degree coverage in medium-large rooms up to 400 square feet. Easy on the eyes and air. The top-fill 0.97-gallon tank features up to 45 hours of runtime with automatic shutoff when out of water, plus adjustable mist settings. Clean tank technology helps protect the tank from mold and mildew while the included essential oil tray and built-in night-light offer relaxing aromatherapy.