theGizmoMart Mini Portable Bottle Cap Cool Mist Ultrasonic Humidifier Air Purifier Diffuser with USB Cable (White) COOL MIST: Ultrasonic portable cool mist humidifier diffuses water mist to increases air moisture and removes dust. EASY TO USE: Easy to clean & refill, easy to operate with USB cable; Fits various size of bottles or cups. SAFE OPERATION: Auto shut off and energy efficiency; extremely quiet, helping you sleep soundly or work effectively. PORTABLE: Lightweight, small and portable. Convenient to use at any-time and anywhere. CALMING LIGHT: Build-in LED light giving a soothing calming effect; It can also serve as a night light.