DESC: The Air-O-Swiss Ultrasonic Warm Mist Humidifier uses high-frequency vibration to generate a micro-fine mist. It has a built-in hygrostat and an output regulator button. A replaceable demineralization cartridge ensures a hygienic, pure water mist, without lime scale or mineral residues. When operated with the pre-heating function, the water is heated to 176°F before it enters the nebulizer chamber. The mist exits the humidifier at a comfortable 104°F, so the mist does not cause room temperature to fall. Pre-heating also keeps the water cleaner. The Air-O-Swiss Ultrasonic Warm Mist Humidifier also features Automatic and Sleep modes. Automatic mode maintains ideal humidity you select in relation to room temperature. When the Sleep mode is set, the unit shuts off after eight hours.