The NUK Powered by Bionaire Ultrasonic Cool Mist Humidifier helps relieve the effects of dry air, so children can breathe easier and sleep peacefully. It has a cool refreshing mist to increase the air moisture in your child's bedroom. It has a large 1.5 gallon tank that runs for 24 hours. The variable knob control allows you to easily adjust the level of humidification to your desired setting. The humidifier is virtually silent and won't wake a sleeping child. The built-in amber nightlight is proven better for uninterrupted sleep than standard blue or white nightlights which depress the sleep hormone melatonin. A patent-pending Child-Resistant Plug Lock makes it hard for your child to pull the appliance cord out of the wall electrical outlet. The humidifier automatically shuts off when the tank is empty. The NUK® Ultrasonic Warm & Cool Mist Humidifier is uniquely powered by Bionaire Technology. Features include: Cool mist operation Variable humidification settings Powered by Bionaire Technology Built-in amber nightlight Removable 1.5 gallon tank 24 hour run time Automatic shut-off Filter-free, easy to clean Virtually silent Ideal for small or medium size nurseries or bedrooms 1-year warranty Voltage 120 volts