OIL DIFFUSER will automatically and safety shut off once the water runs out so the unit doesn't overheat. The 500mL tank is large enough to use in any size room and the tank is easy to clean and maintain so the unit lasts for years DIFFUSER FOR ESSENTIAL OILS features a smart touch panel to easily control the lighting, high or low mist mode and a 1hr/3hr/6hr timer that will keep misting until the water runs out. COLORFUL MOOD LIGHT has the ability to cycle through 7 different colors or stay on one. It is great for creating a calm uplifting atmosphere during meditation or to use as a night light. It can be used as a humidifier or as a room air freshener