BakkerElkhuizen S-board 860 Bluetooth Re User manual - Manual (Page 3)

LED function description:
LED function type.
Num lock
Caps lock LED/ID pairing
Green: Battery charge
Red: Battery low
How to charge the batteries
When the battery power is low, the Battery
low LED will flash and turn red. Use the
Micro USB retractable cable to connect to
an USB port of your computer to charge
the batteries. During charging in process,
you can continue using the keyboard.
Note: this Micro USB connector
is only for charging batteries use,
there is no data link function.