This is a KELLY resin horn mouthpiece, Crystal Blue. It appears to be modeled after the Holton DC. The shank isn't specified, but it's likely an American shank. (It fit perfectly on a paxman M23) Some people also use it with Alexander horns. Rim Inner Diameter: 17mm Throat Diameter: Medium Cup Depth: Deep It's only been test-played a few times and is in clean condition with no shank scratches, but please consider it a used item and understand that it is sold as-is, with no returns or exchanges. -------------------------------------- KELLY mouthpieces are known for their rich color variations, smooth feel, and rich tone! The polycarbonate resin LEXAN used as the material has water-like transparency, unparalleled impact resistance, and high heat resistance up to 161°C. It boasts strength exceeding that of iron per unit weight, making it an extremely excellent material. This mouthpiece is recommended not only for players who are particular about tone and appearance, but also for those with metal allergies. Because it is made of polycarbonate resin, it is not easily affected by the outside air, making it ideal for playing outdoors in cold weather.