DESC: The Slant Fin Warm Mist Germ Free Ultraviolet Humidifier with 2.0 Gallon Capacity (model GF220)provides the humidity you need without the germs and white dust that other humidifiers can produce and distribute throughout the room. With the GF-220, Slant/Fin has created one of the best humidifers on the market, eliminating the weaknesses of many other humidifiers. The GF 220 warm mist humidifier uses ultraviolet radiation and vaporisation to dispose of 99.99% of the germs in its mist -and the generous 2.0 gallon water tank can run for a day or more before requiring a refill.