Holmes HM1855 4-Gallon Digital Humidifier Wick-filtered humidifier provides cool mist for dry indoor air Delivers up to 4 gallons of cool moisture per day Humidifies medium to large rooms--up to 900 square feet Runs for up to 40 hours on one filling at slow speed Measures 14-1/4 by 17-1/2 by 12-3/4 inches; 6-year limited warranty