Fine tune your air flow for a healthier, happier home. The Pure Guardian Ultrasonic Humidifier emits a soothing cool mist over a 10 hour period using ultrasonic technology that keeps operation quiet, so it won't disturb light sleepers. A mold- and mildew-resistant tank ensures air stays pure and fungus-free. | Pure Guardian H920BLCA 10-Hour Ultrasonic Cool Mist Humidifier