Willie's APOLLO 575VDJ Model Trombone Mouthpiece Inner Rim Diameter: 25.75mm Throat Diameter: 7.1mm Cup: Deep Almost unused, so it's like new. Here's a description of the product: The sound of the trombone in an orchestra 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 design and made detailed adjustments from scratch. It incorporates numerous new features, such as the J-rim, which is designed with the Japanese dental structure in mind, the APOLLO Throat to improve the tone in the low register, and a body with Resonator processing for a rich sound. Even the thickness of the shank went through multiple prototypes, which were actually carved and tested. That's all. Thank you for looking.