The HoMedics® Warm and Cool Mist Ultrasonic Humidifier uses ultrasonic technology for whisper-quiet operation. It produces a micro-fine mist with cool or warm mist options, to improve the air quality of your home in any season. The easy to remove and fill the 1.4 gallon tank, runs for up to 65 hours per filling. This humidifier also features auto shut-off protection and a built-in timer. Clean Tank technology helps prevent the growth of molds and mildews on the surface of the tank.