A tennis ball is very important equipment to play tennis sports.  In most sporting events tennis balls are yellow in color.  To win tennis game, one of the important factor which mostly depend is color because the visibility of the tennis ball is observed by it. Due to  bright yellow color player ensure that they can see tennis ball quicker and more clearly, it also ensures that the audience can see more easily during tennis tournaments.
The diameter of tennis ball approximately 6.7 cm (2.63 in.) and weight of minimum 56.7 and maximum 58.5 grams. A best tennis ball totally depends on quality of the rubber which is used in it and glue used to join the two halves of hemisphere .
There are 2 different types of tennis balls which are pressurised tennis ball and pressureless tennis ball.

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Pressurised tennis balls are also known as gas filled tennis ball because this tennis ball is filled with air and uniformly surrounded with rubber material. The ball consists of two rubber hemispheres joined together under pressure, before joining together a small pellet of solid compound is attached to it. The internal pressure must be greater than the external pressure. During the process, the small pellet changes into a gas which generates pressures inside the tennis ball. That is why this ball called a zero-pressure ball or a non-pressurised ball. Balls are changed during tournaments because they begin to lose their gas after opening the can. That is one reason why professional players change tennis balls every nine games .
The pressureless tennis ball is made up of slightly harder rubber which have equal pressure in the core of the tennis ball. For beginners and less demanding tennis player, a pressureless tennis ball is better for them. Pressureless tennis balls with a very low bounce and  have been specially developed for young and developing tennis players. The pressureless tennis balls have a longer lifetime than zero-pressure ball. These tennis balls are not soft as gas filled tennis ball. These balls are hard core in nature. Even with a hole in the pressureless tennis ball you can keep playing tennis.