PowerPure 4000 Warm and Cool Mist Ultrasonic Humidifier Humidifies up to 500 Square Feet; Both Warm and Cool Mist Features Ultra-Quiet Operation; Emits up to 2.3 Gallons Per Day Reservoir Holds 1.32 Gallons of Water for All Day Operation No Expensive Filters! Features a Permanent Ceramic Filter that Softens and Keeps Water in Reservoir Fresh Bottom Fill Design; Light, Easy to Carry Water Tank