This mouthpiece was developed for Mike Vax, a high-note hitter who played in Stan Kenton's band and is also a renowned clinician. It's a Marcinkiewicz mouthpiece, popular among professional musicians in studios and big bands. The inner rim diameter is slightly smaller than a Bach 10-1/2. The rim is flat and thick. Therefore, the outer rim diameter feels slightly larger than a Bach 10-1/2. The outer edge of the rim has a slightly gentle cushion rim shape. The rim is very comfortable on the mouth. The inner edge of the rim is somewhat distinct. The inner edge of the rim has a shallow undercut, designed to prevent the lips from touching the cup wall, reducing fatigue. The cup is a shallow UV cup shape, about halfway between a Bach D and E. The shoulder angle inside the cup before the bore is distinct. The throat is #28 (3.57mm). The backbore is a Warburton 5. The shank end thickness is about 0.9mm, making it thick. It has a moderate resistance and a very good response. It produces a brilliant sound with an edge. It feels like the vibrations within the cup are efficiently transmitted to the instrument. Please feel free to ask if you have any questions.