The Vicks filterless humidifier helps relieve cold symptoms, nasal congestion and more. It has 3 different mist settings for precise adjustments. With a 1-gallon water tank, this Vicks cool mist humidifier can work continuously for up to 24 hours on a single refill. The tank detaches from the main unit for easy refilling and cleanup. Its whisper-quiet operation lets you use it in your childs nursery or overnight. This quiet cool mist humidifier is ideal for rooms between 100 and 300 square feet.