Enjoy quiet sleep without congestion, coughing, or dry mouth, DREO baby humidifier's ultrasonic atomization brings noise down to 28dB, while its 4L tank provides up to 36 hours of moisture without the need to refill. Thanks to its high-frequency atomization process, DREO humidifiers for bedroom releases 5?m Ultrafine mist and lighter mist particles, allowing humidity to spread evenly across the room without wetting surfaces.