TOP FILL TANK: Traditional bottom-fill tanks with a screw-on cap will leave a trail of water on the floor and require a deep basin to fill the tank completely. The top-fill design of the TOSOT humidifier eliminates mess and is super easy to fill in all types of sinks. MULTIPLE MIST MODES: Depending on how much moisture you want to add to the room you can choose from the different mist output levels. Simply short press the control button to cycle between high medium and low mist output modes. The humidifier can run from 12 hours (on high) up to 28 hours (on low). SLEEP MODE & Auto-Off Protection: This humidifier will run silently while you are sleeping thanks to a peak sound level of 28 decibels. You can also shut the LED tank light off so that you can catch some Z's in complete darkness. If the humidifier runs out of water while you're asleep the auto-off protection will kick in to protect the humidifier from damage.