This large 1 Gallon (3.8L) Ultrasonic Humidifier instantly vaporizes water into the air for up to 20 hours. It is perfect for use in any room at home that suffers from dry air. An integrated tray that allows you to add your own essential oils means this can also be used as an aroma diffuser should you wish to add a relaxing smell to the air. By keeping your living space at the right humidity, you can help prevent sore throats, colds, flu, congestion, and dry skin. Studies have shown that keeping indoor air at a humidity level of 40 to 60% reduces the survival of flu viruses in the air.