Tuba Mouthpiece YAMAHA 67C4 Brand new, unopened. This is an all-around model, ideal for Bb and C tubas. Features: Standard series using common brass for the mouthpiece. Smooth attack and easy control. A wide variety of lineups to meet each individual's style. 67C4: An all-around model, ideal for Bb and C tubas. It produces a consistent, calm sound with rich, powerful volume. Rim Inner Diameter (mm): 32.06 Throat Diameter (mm): 8.10