Willie's horn mouthpiece. Model: AST Cup Internal Polish: Mirror finish Rim Inner Finish: GP (Gold Plated) Inner Diameter: 17.45mm Throat Diameter: 4.9mm Cup Shape: U-cup Shank: STD (Suitable for 80% of horns, including Wenzel Meinl, Hans Hoyer, Wilson, Paxman, Holton, etc.) If you own the instruments listed above, this mouthpiece should fit. Please try it. No history of being dropped or repaired. There are slight scratches on the shank, but it will fit perfectly on instruments with STD shanks. Please check the images and make your judgment. If you have any questions, please comment.