The Germ Guardian Humidifier uses nano-silver technology to prevent microbial growth within the unit, stopping mold growth for a healthier breathing enviroment. The ultrasonic technology with option for warm or cold humidification set this humidifier above the rest. Warm humidification maintains an 80 degree temperature to kill low-temperature bacteria. This unit offers you a low water indicator that lets you know when it"s time to refill the container, a variable spray function allows you to adjust the volume of spray output. It has a humidity auto-adjust that senses humidity in the environment and automatically adjusts to pre-set level. The quiet operation makes this a great humidifier for any room.