Mouthpiece for gray-beards ?

[CharlieB]

I found this mouthpiece in the case of an old trombone bought from ebay.
Stamped H.N. White Co.28 Equa-tru.
Probably from the 1930's ?
Inner rim diameter = 0.980" Bore = 0.238"
Cup depth same as a Bach 9, but different shape.
A good player in my .500 horns.
Probably considered a "big" mouthpiece in its day ?
Is anybody here familiar with this mouthpiece ?