The HoMedics TotalComfort Plus Ultrasonic Humidifier produces a visible warm or cool mist for up to 65 hours of runtime. The warm mist setting kills up to 99.9% of bacteria so you can breathe easier knowing you’re helping to protect against germs. A night-light, essential oil tray, and auto-off timer ensure ambiance and premium air quality control in large rooms up to 547 sq. ft. The 1.4-gallon tank features Clean Tank Technology that helps protect the tank from mold and mildew.