Annealing process: 300 series ordinary steel obtains high-hardness steel-titanium alloy through alloy steel gas oxidation technology. After metal heat treatment, stress is eliminated, size is stabilized, material structure and composition are uniform, the vibration stability of steel is improved, noise is eliminated and "iron knocking sound" is reduced. Type C is more affordable than Type A and Type B, and has a larger audience, which can meet the needs of most people. It is suitable for normal class use and beginners, and can also be used for professional performances.