[2 in 1] Car Air Humidifier and Aromatherapy Essential Oil Diffuser (Blue) Relief from dry air, cold, flu, cracked skin in the winter and cold weather Simply plug the humidifier into your car's cigarette lighter,100ml water and it works. Press the button to change the mode ,humidifier and Essential oil Diffuser(Works with ordinary tap water, plus 2 to 3 drops of essential oil ) Note:It must be used after the car running,please do not use it when there is no water in the bottle