The raw rubber is similar in specifications to the ordinary positive rubber, but the glue content of the colloid is larger than that of the positive rubber, so the particles are softer and the elasticity is relatively large. Compared with the positive rubber, the main feature of the raw rubber is that the speed of the ball is significantly faster, which is suitable for athletes to actively exert force. When hitting the ball, in the case of heavy hits, the ability to control the ball is better, and the hit ball sinks slightly. The main disadvantage of raw rubber...