The Challenge humidifier uses ultrasonic humidification to release water particles back into the air to increase the water moisture levels in the room giving a much lighter and fresher feel. The vapor capacity is up to 250ml per hour. Easy clean filter. Suitable for room size 25m. Ultrasonic humidification. 3.2 L water tank. Visible water level. Auto shut-off. 1 speed setting. Variable control. Quiet operation. Washable filter. Size H34, W20, D22cm. Low energy consumption.