PureGuardian Warm and Cool Humidifier with Aroma TrayThe 120 hour* ultrasonic features an easy to fill large 7. 57 L (2 gal.) tank. This humidifier features Silver Clean protection in the tank to fight the growth of mould and mildew on the surface of the water tank. Thanks to ultrasonic technology, it disperses a fine mist into the air, and is ultra quiet making it ideal to have on while you sleep. The humidifier is equipped with the option for warm or cool mist and 3 speed settings. A low water