1) Turning on or off

Three green lights flash when you press the on button. Three red lights flash when you turn Buzz off.

2) Microphone sensitivity level 

When you touch the plus or minus buttons on Buzz, one light means you are on low sensitivity, two lights means you’re on medium, three lights means you’re on high sensitivity.

3) Battery level low warning and battery charging

If your Buzz is very low on battery, it flashes 3 red lights to warn you that it is almost dead.

4) When you plug your Buzz in to charge, the lights indicate how full the battery is.  When the battery is fully charged, it will show 3 green lights.