This is a vintage Penzel-Mueller New York Hard Rubber tenor mouthpiece in nearly perfect condition. No facing number on the mouthpiece. The tip opening looks relatively small, but the tip is thick enough that you could have this one opened up a lot if you like the sound. Since it’s a vintage piece, the rubber is probably excellent!
Somewhat narrowed side walls with a low floor should give this piece a sound with some presence, but not bright.
A Vintage Martin Cap and Ligature come with it.