VicTsing Cool Mist Ultrasonic Aroma Essential Oil Diffuser This VicTsing Cool Mist Ultrasonic Aroma Essential Oil Diffuser ($30, originally $53) has four settings; let the fragrance mist from one hour, three hours, six hours, or continuously. Image Source: amazon.com VicTsing Cool Mist Ultrasonic Aroma Essential Oil Diffuser $30 from amazon.com Buy Now