The Airome 100 mL Medium Ultrasonic Essential Oil Diffuser works by using slight vibrations to emit a fine mist of cool water carrying your favorite essential oil. All Airome products are made using quality materials of ceramic, porcelain, glass, and metal. The medium 100 mL diffuser allows you to enjoy a mist of essential oils for up to 8 hours. From traditional and classic to modern and geometric, we've created a variety of styles for every mood and decor. Your choice of two settings of intermittent, which will run for 8 hours, or continuous, which runs for 4 hours. Diffuser automatically shuts off when water runs out.