Large cup diameter and barrel backbore gives a big, open sound.
The Steven Mead Ultra X series is for players looking for a sound that has more brilliance than the standard Ultra Series or classic Steven Mead Series. The cup has been rounded to a more defined bowl shape which adds more brilliance to the tone and provides better upper register response. The rim has been altered to have a slightly sharper inner edge which increases articulation response and accuracy.
Had been using a Denis Wick 6 1/2 meant for a trombone as that’s what came with my horn. FYI don’t use a trombone mouthpiece on a Baritone horn even if it’s a small shank there not designed to produce the correct sound. The SM4UX is exceptional in response, accuracy, and tone. Plays very easy and gives good control. Some reviews of the ultra X state it makes the horn bright and loud compared to the standard ultra 4 I find this to be rubbish. The ultra X to me just gives me more control and is far less tiring to play.