Windows 10: where to find the current battery level of my wireless keyboard and mouse?

I have a tiny device plugged in an USB port, that talks to my keyboard and mouse. In the settings for Bluetooth other devices , it seems to appear as Mouse, keyboard pen , and underneath, in a box: USB Receiver . The only corresponding control seems to be: Remove device ; no further options. How do I tell the current level of the batteries in these devices? EDIT: additionally, I have just noticed that my Bluetooth is actually off . So however this little USB dongle works, it's separate from Windows' onboard bluetooth.

Question by Levente on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.