I love this diffuser. It has a large tank.. 700 ml.! It can run up to 12 hrs.! It automatically shuts off when it runs out of water. Simple to use..fill tank with water (comes with measuring cup)..put your favorite oil..choose timer from 1 hr-2hrs.-3hrs. or you can just leave it on for 12hrs or until it automatically turns off when the water is gone. Can put on at night and not worry about it running out of water and staying on. Can also be used as a non-aromatherapy humidifier or an air purifier to put some moisture in the air for dry cough, sinus irritation or dry skin. There is a button to control the light, you can cycle thru different colors (seven of them) , remain solid (if there is one you love) or turn it off( if light bothers you at night) . I love the colored lights and love to cycle thru them all at night. The last button allows you to control the mist..high or low. I love to run mine at night with different scents of oils to help me relax ans enjoy the light show. I received this product for a discount. All my reviews are based on my own experience and evaluation of the product so that others can benefit in finding quality products that meet their needs & expectations.