Yamaha Trumpet Mouthpieces were, some 40 years ago, originally designed by Schilke, and that is why to this day they still use the same numbering system. The same can be said for the range of Yamaha trumpets, although it wasn’t long before they moved away from Schilke’s original designs and started introducing their own ideas. Anyway, back to their mouthpieces.
They produce a large range of widths and depths and with some, like the 14a4a they have a tight backbore to suit the “Screamer” or lead player in a big band. For the Orchestral player the 16C4 is popular and it is this mouthpiece that is included with the range of Xeno trumpets.