This car humidifier : Using technology of ultrasonic nebulization and 113kHz frequency transform the water into 6um microminiature droplet, spread the essential oil more smoothly with the natural fragrance, volatilize smoothly, humidify air, make the skin more confortable. Humidifying effect: Remove static electricity,dust inside the car.purifying dirty air to prevent cold, germfree humidifying,reducing tire to make freshing. Humidifying while charging: Duel USB ports,charging two devices simultaneously, And dual USB port output 5V/2A, can charge your devices fast. Auto Shut Off Protection: Waterless auto shut off.