Ultrasonic humidifier uses a metal diaphragm vibrating at an ultrasonic frequency to create water droplets that are expelled out into the room to help maintain the desired humidity level. An ultrasonic humidifier is virtually silent when operating. Features include cool mist humidification, .23 gallon tank capacity, will run approximately 8 hours depending on atmospheric conditions, low water indication and there are no wicks or pads to replace. Space saving design is great for apartments, the office, or small bedrooms. 7.9" W. x 8" H. x 3.5" D. 2 year limited warranty.