Looks like what we call a correction bit based on what i can see of the shape of the port( no matter what it is called a curb bit due to the shanks on either side of the mouthpiece, and this one as another poster said is a ported mouthpiece, they can have jointed ones. )
Any marker's Marks on it? the rings at the bottom of the shanks tell me that it was likely meant to be used with romel reins and rein chains.