Crane USA Personal Cool Mist Humidifier ULTRASONIC COOL MIST: Increases air moisture for easier breathing and a good nights sleep AUTO SHUT-OFF SENSOR: Humidifier automatically shuts off when the water level is low NO FILTER REQUIRED: This humidifier does not require a filter, but for homes with hard water, demineralization filters can be purchased and used with this unit 21 OUNCE TANK: Removable 21 ounce water tank runs whisper quiet up to 8 hours 360 MIST NOZZLE: With variable mist output and humidity control settings VOLTAGE  120 V, for domestic use only