This is the evaporative humidifier with an antimicrobial wicking filter that captures allergens while preventing the growth of harmful mold and bacteria. The space-saving, mist-free humidifier uses natural evaporation plus whirlwind fan technology to keep a room at a comfortable relative humidity. Besides removing allergy-provoking dust, pet dander, smoke, and pollen from the air, its innovative filter also dramatically reduces the discharge of white dust typically produced by ultrasonic humidifiers. Its 2.8-liter tank lasts up to 25 hours (depending on setting) before needing a refill. With four fans speeds, built-in nightlight, and 2/4/8-hour timer. AC adapter. For rooms up to 500 sq. ft. 13 1/2" H x 9 1/2" Diam. (4 1/2 lbs.)