Mouthpiece selection Our standard trombone and euphonium mouthpieces are arranged on our specification chart in a logical ascending order from deep to shallow, No.5GW to No.15 in tenor, No.1 to No.8H B.S. / 61/2AL in bass and No.5G-S to 7G-S in Euphonium/Baritone. As rim size does not directly correspond to cup depth, please observe inside cup diameter for finding optimal response. Comparisons The comparison listed on this page offers rough comparisons only. The comparisons are given for casual references only.Note Please note all Euphonium/Baritone mouthpieces come with an "S" (symphonic) backbore. "S" (symphonic) backbores available in Tenor and Bass Trombone mouthpieces on special order.