The Holmes HM6600-U Cool Mist Tower Humidifier features: Evaporative Wick Cool Mist Humidifier—uses a wick filter to trap minerals and impurities allowing a cool invisible mist to evaporate. Filter Check Filter Monitor—automatically monitors filter condition and indicates when a new filter is needed. 1-Touch Humidistat With Clear View Carbon X— helps eliminate household odors. 3-gallon performance capacity. 36-hour run time. Ultra-slim space-saving design. Measures 11.5″ x 11.5″ x 29″.