The mouthpiece that came with my Chineese horn says it ts a 7C. I have never had a horn/mouthpiece combination that favors the low register as does this one. Low A is very natural and pure for these old lips whereas my former trumpet (60 years ago) could not begin to reproduce this note. Would it be the horn or the mouthpiece? Or could it just be that I haven't limbered up the lips as yet?