Warburton mouthpieces are designed as a system that facilitates the brass player. Allowing them to choose a rim diameter, cup style and depth, with a back-bore to best balance the players sound and resistance. The aim is to give the player the most efficient mouthpiece to be able perform in any given playing situation.
The Warburton mouthpieces are a two-piece system consists of fully interchangeable "TOP" and “BACK-BORE" sections. Due to the multiplicity of demands placed upon the modern brass player, the various cup designs have been chosen for ability to produce the most desired sound in any playing idiom.
In this case we are looking at the Warburton “TOP", where they have tried to give the player a variety of size both with options in rim shape/width and cup size (depth/diameter). There is a list of their top sizing to peruse.
Warburton back-bores are available in thirteen standard sizes for Trumpet, Cornet, Schilke Piccolo Trumpet and Blackburn Piccolo Trumpet.
I think it's a common journey for most trumpet players to find the "Holy Grail" mouthpiece, and it can be a never ending search.
I've been looking for the past 30+ years really. Starting the trek with a Yamaha student mouthpiece, with Bach, Stomvi, Marcinkiewicz, ACB, Monette, Custom Made, a few more in there too but ending up on this Warburton MC #3 top on a STD Back-bore #4.
I feel with the Warburton brand you can find your perfect match, well as close as possible. They have so many options to help make your decision.
End your never ending search and go Warburton!