Honeywell Cool Mist Ultrasonic Humidifier Auto Shut Off White 1 Gallon Tank New.. Honeywell Cool Mist Ultrasonic Humidifier Auto Shut Off White 1 Gallon Tank New Breathe easier with the Honeywell Cool Mist Ultrasonic Humidifier (HUL535W). It runs quietly and requires no filter, allowing for easier maintenance. A variable dial mechanism provides a flexible way of adjusting the moisture output for up to 24 hours of constant mist (from a full reservoir). It also features a directional outlet for optimal humidification. Suitable for small- to mid-sized rooms, the white humidifier automatically shuts off when the tank is empty.. Honeywell Cool Mist Ultrasonic Humidifier HUL535W, White: Variable moisture output settings Directional mist outlet Ultra quiet operation No filter required Auto shut off when empty Ultrasonic humidification technology Designed for medium rooms Honeywell humidifier runs up to 24 hours per filling on low setting 1 gal tank capacity Large opening for refills and cleaning