The PureGuardian H910BL 14-hour Ultrasonic Cool Mist Humidifier guards against problems caused by dry air in the home. Cleanliness matters! Unlike other humidifiers that grow slim on the water tank surface, Silver Clean is embedded in the tank to fight the growth of micro-particle formation on the surface of the water tank. Thanks to ultrasonic technology, it disperses a soothing, cool mist into the air and is ultra-quiet making it ideal to have on while you sleep. It is great for tabletops due to its compact size. A low water indicator light lets you know when it's time to refill the water tank and the night light feature makes it a great addition to kids' rooms! PureGuardian humidifiers create a better home environment for those suffering from colds, discomfort and dry skin. It is important to only use GENUINE Guardian Technologies replacement parts to maintain product performance.