The ring of lights around the power button changes color based on current air quality:

• Blue: Very good
• Green: Good
• Yellow: Moderate
• Red: Bad

Tapping the ‘Display Off’ button turns off all of the device’s indicator lights and the night light. On that subject, the night light features two levels of brightness. The 600S also has a light sensor, which automatically triggers the Display Off function if it detects that it’s been put in a dark room. The device’s lights will also automatically illuminate if you turn the lights on in a dark room. However, it’s important to note that you have to enable this function through the VeSync smartphone app.

The VeSync companion app also allows you to remotely adjust the device’s fan speed, set operating schedules, and send filter replacement reminders. You can also use it to view a real-time estimate of air quality.