Diffusing essential oils for therapeutic use is a breeze with the versatile Optima Therapeutic Diffuser. With its variable air flow control, the Optima diffuser can be turned up to powerfully diffuse oil into a large area, such as a shop, office or home (up to about 1500 square feet), or turned down to quietly fragrance a smaller room in minutes. The all-glass Ultima nebulizer is specially designed to hold up to 15 ml of oil, while still being able to diffuse with only a few drops left in the nebulizer. The stylish blue air pump on this diffuser measures 7" x 4" x 3" in size, and produces sound levels of approximately 51dB on low speed and 55dB on high speed. For U.S. standard power supply only (110-Volt AC, 60-Hertz). In other areas with different types of power supplies, a power converter must be used.