This is the signature model of Al Hirt, the "Don" of the trumpet world. The Jet Tone Al Hirt Model D makes controlling high notes easy and reduces fatigue. The inner rim diameter is about the size of a Bach 5. The rim is flat and quite thick. The apex of the rim is on the outside, and the lip feels stable inside the cup, providing a comfortable feel. The outer rim diameter feels about the size of a Bach 1, a bit larger. The design is such that it doesn't hurt even with hard pressing and reduces fatigue. If you are interested in more detailed sizes, shapes, playing feel, and used or new mouthpieces, please search on Net Brass. Please check the images. There are no major scratches or dents that would affect playing. There is some wear, but it comes with the original paper box. Please refrain from comments asking for a price reduction. Instant purchase is OK.