The USB diffuser has an elegant white ceramic sphere that emits a subtle, dappled light bringing a sense of calm to your space. Ultrasonic technology dispenses the soothing aromas of essential oil into the air. Features:. Power Supply: power point USB adaptor or USB port (i.e a computer). Made of Ceramic and BPA free plastic. Dimensions: D 12.5cm x H 15.5cm. Quiet operation. + 2 hour timer setup. non chemicals or heat required. 120ml water capacity.