I can spend all day in the altissimo on alto/tenor, but baritone was always problematic for me. I never spent the time on it. Selmer started offering altissimo register keys on their series III horns, so I decided I'd try making a quick one, by opening the spit key on the bow. Great! This hole is about two inches too far down the tube, but still, it really works. The notes just popped out. Anybody tried using one?