The Guardian Technologies™ PureGuardian® 14-Hour* Ultrasonic Table-Top Humidifier is a cool mist humidifier. Unlike other humidifiers that grow slimy mold on the water tank surface, the ultrasonic humidifier uses Silver Clean™ technology embedded in the tank to fight the growth of mold and mildew on the surface of the water tank. Thanks to ultrasonic technology, it is ultra-quiet when it runs making it ideal to have on while you sleep. It's small and compact and stands less than 9-inches tall. It's the perfect size for travel, for a desktop, for a child or baby room and bedside. It weighs just 1.35 pounds, features a .21 gallon tank capacity, and it runs continuously for up to 14-hours.