### Chinese: 它们强度很低，球打到拍子上面，振动非常大，硬球顶不住，高手都很难驾驭。
### English: Their intensity is very low. When the ball hits the racket, the vibration is very large. The hard ball can't stand it, and it's difficult for masters to control it.

### Improved English: They are low in strength, and there will be too much vibration when the ball hits on it; it cannot withstand hard balls, and even professional cannot handle it.
