APOLLO 595VDJ Trombone Mouthpiece Inner Rim Diameter: 25.95mm Throat Diameter: 7.1mm Cup: Deep Used for about a year, so there is some blackening, but it can be fixed with polishing. The following is a product description: The sound of the trombone in orchestras has various characteristics depending on the country. Germany has a clear and resonant sound, France has a dazzling and brilliant sound, and America has an impressive, robust, and powerful big sound. The APOLLO series was designed for this modern American symphonic sound. Mr. Hiroki Sato, principal trombone player of the Tokyo City Philharmonic Orchestra, supervised the project and made detailed adjustments from scratch. It incorporates numerous new features, such as the J-rim, which is designed with the Japanese dental shape in mind, the APOLLO Throat to improve the tone of the low range, and a body with Resonator processing for a rich sound. Even the thickness of the shank was tested by actually cutting and testing several prototypes. That's all. Thank you for viewing.