Hi: I tried using this bit on my tuba, to see if it would lower the pitch some. Well, it did not do very much lowering of pitch. It does what it is supposed to do. It will help small people get the proper angle on a tuba or sousaphone where you usually need two. Be careful on the Sousaphone, to not yank the bits around, or the goose neck will come apart, and is a big repair bill. You need to twist these bits into the proper position, and do not hammer them in. If they don’t want to stay put, the goose neck is probably not really round at the outer end. That is an easy fix with a large reamer. Let an adult do it. My motto: "Tuba is a low blow" especially if played wrong! Ed