YAMAHA SL-51C4LGP Trombone/Euphonium Mouthpiece Large Shank Rim Inner Diameter: 25.23mm Throat Inner Diameter: 6.92mm Features a slightly shallower cup than the 51, allowing for powerful playing with a large volume. Produces a full sound across all registers, making it suitable for symphony orchestra players. There are some lines and minor scratches due to insertion and removal from the instrument. Please understand that this is a used item. Thank you.