 | This efficient air humidification technology uses high-frequency vibration to generate a micro-fine mist. A fan blows the mist into the room where it immediately evaporates. The 7133 ultrasonic humidifier requires little power, has a built-in hygrostat and an output regulator button. 1.8 Gallon, 600 Sq. Ft., 8 Hours, Humidistat Control Number of Reviews: 5 | Ratings:  | Best deal: $169 $169 - $170 from 3 stores. |