Logitech MX Master Frequently Asked Questions Manual page 50

4. Follow the on-screen instructions to finish connecting your device.
 +Mouse battery status indicators
Your mouse uses LED lights to indicate battery status. When you turn the mouse on, the LEDs
light up to let you know the battery status and then turn off to conserve battery power.
LEDs
Three green
Two green
One green
One red
You can also use Logitech Options to receive battery status notifications, including low charge
warnings. If you don't have Logitech Options, you can get it from your product's Download
page.
Description
100% Charge
66% Charge
33% Charge
10% Charge