It is too late now of course but if it was a transmitter wouldn't it have been sweet to have some group jam the frequency during the debates?
The object looks WAY too bulky to be a radio device, I mean come on they would have something pocket sized for that. As for the bulletproof vest
theory, I really can't see him wearing one during a controlled situation like that.
My theory is that he has serious health issues and that he wears some kind of brace to help with that, wouldn't be the first time they covered up a
President's physical problems.

