It’s a 19th Century steel Austrohungarian driving bit with an arched mouth – that much is clear.
However on its near (left) side it has a Pelham type ring for a snaffle rein, but on the off (right) side it does not. I suspect it was removed after manufacture rather than having broken off because it has a smooth finish.
Also on the inner surface there is a diagonally slanted slot and a recess for a stud – the inner surface of the off side has a “patch” of steel, presumably covering the slots on that side.
Possibly the slots held some sort of crest or decoration, and this bit belonged to the nearside horse in a pair , so it was not felt necessary to decorate the offside ? But that doesn’t quite explain the rein rings… Any ideas ?