Holmes HM1230 Cool Mist Humidifier for 600 Square Foot Room Cool mist humidifier; suitable for small to medium rooms Runs up to 24 hours on 1-gallon tank; maximum output of 2-1/2 gallons/day Circular extended-life wick filter with built-in monitor Microban antimicrobial product protection 11-1/2 by 9-1/2 by 8-1/2 inches; 2-year warranty