Black & Decker BXHU095 50-Hour Ultrasonic Cool Mist Humidifier, 1-Gallon Ultrasonic technology is ultra-quiet when running making it ideal to have on during the day or night The 1-gallon water tank allows for 50-hours of run time (on the lowest setting) The mist output is customizable thanks to variable speed controls On/Off night light No evaporating filters to clean or replace