<p>Mainstays Ultrasonic Cool Mist Humidifier with Aroma AE00-23480BC uses ultrasonic high-frequency technology to convert the water into particles that are dispersed into the air evenly, with 0.31 Gallon Capacity, Nightlight, and Auto Shut Off functions, coverage area:219 sq ft,which can offer many benefits to your environment, making your home a more comfortable and enjoyable place throughout the year. The relative humidity is the amount of moisture in the air compared to how much moisture the air can hold. the higher the RH, the more humid it feels. warm air holds more moisture than cold air. Raising the humidity level in a cool, dry room can make it feel warmer and more comfortable. Humidifiers offer many benefits to your environment, making your home a more comfortable and enjoyable place throughout the year.</p>