I bought this because I liked the look of it, rather than a standard mouthpiece, for event band work. It does look cool.
Does it make me sound better? If it does I don't really hear it.
It went on my bach 2 1/2 c mouthpiece, and its a very tight fit, and not exactly flush either. I think it produces a slightly richer sound but its a very minor difference, as all brass players know the only thing that will improve your sound is practice. Buy it for appearance but don't bother if you're looking for a musical quick fix.