The product guards against problems caused by dry air in the home. It is ideal for use in small and medium-sized rooms. Unlike other humidifiers that grow slimy mold on the water tank surface, Silver Clean™ Protection is embedded in the tank to fight the growth of mold and mildew on the surface of the water tank. Thanks to ultrasonic technology, it disperses a cool mist into the air and is ultra-quiet making it ideal to have on while you sleep. This top fill humidifier has an optional aromatherapy tray so a few drops of essential oil can be added to create a relaxing atmosphere. The humidifier is equipped with a night light and variable mist control. A low water indicator light lets you know when it's time to refill the water tank. PureGuardian® humidifier creates a better home environment for those suffering from colds, allergies, and dry skin. Note: run time is based on running the unit on low speed, also depends on atmospheric conditions. Do not add oils to the humidifier tank as they can damage the humidifier and void the warranty. Only add essential oils to the pad that is included with the unit.