Warburton mouthpieces are favored by studio and big band musicians. They are compatible with Kanstul, Parke, and others. The inner rim diameter is slightly smaller than a Bach 7. The rim is flat and thick. The rim shape slopes gently towards the outer edge. The inner rim edge has a shallow undercut, making it less likely for the lips to touch the cup wall, resulting in a design that promotes endurance. The cup is deep with a gentle UV shape. The depth is between a Bach C and B. The throat is #28 (3.57mm). When played softly, it produces a warm sound, and when more air is put in, it creates a brilliant sound with a core. It is designed for a wide range of expression. Recommended for solo and combo players. Please feel free to ask if you have any questions.