lockup-matePLUS+ comes with a comprehensive operating manual that lists all the features, how it works, and tips for use. Operation manuals are available here.
The LED displays the status of the lockup clutch, and the following features can be changed using the Switch:
Switch the unit ON or OFF - momentary push to toggle
LED brightness headlight override ON or OFF - push and hold 5 seconds to toggle
SafeLock® - Clutch Protection Technology ON or OFF - push and hold 10 seconds to toggle [This feature can only be changed when Engine is OFF]
See it in operation in the video below.