The Honeywell HUL545WC is a filter-free, ultra-quiet, ultrasonic humidifier provides cool visible mist! It features an essential oil tray for added aromatherapy comfort (essential oil not included), adjustable moisture output settings, dual direction mist outlet, transparent water tank & auto shut-off. 1-gallon (3.79-litre) tank capacity features a wide opening that's easy to fill & clean (cleaning brush included). An ideal fit for medium sized room, it can run up to 36 uninterrupted hours per filling. Many find that a humidifier for the home, bedroom or nursery is an essential part of a good night’s sleep when the air is dry, in allergy season, or when sickThe Honeywell HUL545WC Ultra Comfortᵀᴹ Cool Mist Humidifier quietly produces a visible, cool mist that helps make you and your home more comfortable.