TromboneChat

Dear folks,

does anybody have any information about the King M22 and M23 mouthpieces?
I do find some information about the M21 here but nothing bout the other two.

Does anybody know how they compare to the M21 or what theirs specs are?

Must be pretty rare.
The only King small-bore mouthpieces I am familiar with are the M21 (supplied with King 2B), 28 (similar to M21; supplied with King 3B), and 11M (variant of M21) - these are several decades old.
What mouthpiece is shipped with King trombones these days?

You can find some information about the M22 in the HN White cataloge from 1938.
The M22 was supplied with the King Artists Solo Model trombone.
But so far I couldn't find any information about the M23 though I just bought one last week.