Ultrasonic Diffusers do not heat or alter your oils in any way, and are the most efficient way of dispersing oils into the air. They act as natural ionisers and have numerous health benefits. These are some of the quietest diffusers on the market, each model can function with or without a light and all feature an automatic cut off if they run out of water. Just add cold water and 6-12 drops of your favorite oil. 12 month warranty is included.