15412 This contemporary style evaporative humidifier has an 12 gallon output over a 24 hour period. Suitable for an area up to 2500 sq. ft., based on an 8 ft. ceiling height. Digital LED display of target and actual humidity readouts. Target humidity can be selected in increments of 5% from 20 - 65%. The unit will cycle on and off as require to meet the selected humidity level. The 15412 (12 gallon console humidifier) has a double fill system. There are two reservoirs (i.e. a bottle and the base). The base capacity is 2 gallons and the bottle capacity is 1.9 gallons. The total reservoir capacity (i.e. the base plus the bottle) is 3.9 gallons.