That mouthpiece is slightly similar to the Selmer Table B* piece which came with a near mint original balanced action alto that I own. Mine has the old style chain link and lacks the metal band on the shank. My horn dates to around 1936 or '37 and I'm certain my mouthpiece is original to my horn. Your mouthpiece seems to be a bit earlier than mine. I also have the original ligature and cap. These items are much heavier than the modern counterparts, and the build quality and finish of the mouthpiece is very impressive.