High notes become considerably easier. This is a model that reproduces the old Jet-Tone. The inner rim diameter is about the same as a Bach 18. The rim is flat and thick. The outer edge of the rim has a slightly gentle shape. The outer rim diameter feels slightly smaller than a Bach 10-1/2. The cup has two steps, with the first step dropping vertically from the rim to the cup. The second step is about the same as a Bach E cup. The design makes it difficult for the lips to touch inside the cup. The throat is slightly narrower than a #28 (3.57mm). The backbore is about the same as a Warburton 4. Trumpet mouthpiece Jet-Tone Bill Chase trumpet mouthpiece