The biggest consumption in playing tennis is the ball, but how much do you know about tennis?

1 Pressure ball and non-pressure ball (normal pressure)

The pressure ball has a soft inner bladder, which is filled with air (nitrogen). It will lose its elasticity for a month after it is not used for a long time or the lid is opened. The balls used in the game are all pressure balls. In order to maintain elasticity and stability, the ball must be replaced during the game.

The pressure-free ball has a hard inner bladder that can always maintain a certain degree of elasticity and is mainly used for training. The hitting feel is not as comfortable as pressing the ball. The outer fluff will fall off after being used for a long time.

2 normal and brightening balls

These indicators (duty, extra duty) are marked on the ball barrel. Mainly based on the reflectivity of the fluff on the ball surface. Those with high reflectivity are called brightening balls.

Regular balls are mainly used indoors and on clay. If the brightened ball is used on clay, it will cause the ball to be too close to the color of the court and become blurry.

Brightening balls are mainly used on grass and hard courts.

3 plateau balls

The air on the plateau is thinner and the earth's gravity is reduced. The elasticity of the ball is increased and the ball speed becomes faster than at low altitudes (this is the experience of domestic players playing in Kunming). It needs to be specially manufactured to reduce the elasticity of the ball, but it is difficult to buy it in China. Generally, a non-pressure ball is used instead. The pressure ball can also be opened a week in advance to achieve the effect of reducing pressure.

4 ball fluff function

Fuzz increases the friction between the ball and the air as it flies, making it spin more intensely and slowing the ball down. Give Natto a bare ball, and Nadal's turn will probably be ineffective.

5 Numbers on the surface of the ball

Many children's shoes think this means different types of balls, but they are wrong. This is just to make it easier for everyone to identify their own balls when playing, so that they will not be confused with the same brand of balls used in the next venue. (If you use the same number, there is nothing you can do.)