Tennis ball

Doubles on Court ball external needs by United package of textile materials colours white or yellow, seams need seamless line traces. Ball size should meet the requirements of Appendix I to the fourth article (ball of the test as elaborated in the rules three), weight between 2 ounces (56.7 g) and 2 one-sixth an ounce (58.5 grams). From 100 inches (254 cm) height to the concrete floor of his free fall, and rebound height should be between 53 inches (134.62 cm) and 58 inches (147.32 cm). When imposed on the ball 18 lbs (8.165 kg) when pressure inside the elastic deformation should be something between 0.22 inches (0.559 cm) and 0.29 inches (0.737 cm) between the compression rebound after deformation range should be between 0.315 inch (0.8 cm) and 0.425 (1.08 cm). Deformation data should be both to ball after three axes test are average. 　　In each case the difference between any two data cannot be greater than 0.03 inch (0.076 cm). Elevation 4,000 feet (of 1219 m) high competition, needed two special balls. 　　

First species is except bounce height to between 48 inches (121.92 cm) and 53 inches (134.62 cm) yiwai, also to makes ball of within pressure is greater than the external pressure, other aspects is and above of description full same, this ball usually was called booster ball; second species ball except bounce height to in 53 inches (134.62 cm) and 58 inches (147.32 cm) Zhijian outside, also to makes ball of within pressure about is equal to external of pressure, and can in specifies of competition venues of altitude height keep 60 days above, other aspects is and above of description full same, this ball usually was called zero pressure ball or no pressure ball. 　　

All about ball bouncing, and deformation tests, you will need to comply with the requirements in Appendix I. International Tennis Federation on anything about a certain ball or samples necessary to meet the above standards, or whether you can be approved for competition issues to do so. Such a decision may be a international network itself take the initiative to act, or pursuant to all the real people who are interested in or include any players, equipment manufacturers or national tennis associations and their members to apply for. Such applications and decisions in accordance with the international network of hearing and review procedure.