Also if not totally correct, GoolGaul gave the better answer ..... not for ceiling, but still a hole-cutter .
It's a "bell-saw", also called platedriller here, sometimes ..... there is a widia cutter joined to that rotating central lever, that is acted from an external drill (from the other side) ..... you regulate the lever for the diameter you need, place the silicone gasket on the external border on the plate you need to drill, keep it down firmly and act the drill, and the cutter rotate and cut the hole.
I have a Hi-Fi Bluetooth Stereo Headset similar to this.
Also closely resembles at the heart sensors widely used in hospitals,
and I have recently seen a video console W@@ that has something similar
to control the beats during the game haha
well, at least two of you guessed it right (i was betting that piferal, having to do with medical tools, can have seen one ).
It's a wi-fi photopletismography-oxymetry sensor, this one in particular is made for be used on ear lobe, but the commonly used ones are normally placed on a fingertip.
Whoever of you have one, please feel free to post it :beer: