large tennis ball

ment there are three important time nodes: in 1968, 1972 and 1990. Since 1968, professional tennis ball movement into the Open era (OpenEra), because the four Grand Slam events this year began to accept professional players participating. In 1972, the men's professional tennis ball players association (Association of TennisProfessionals, ATP) was established to better protect the interests of the players. 1990, a new system of ATP Tour officially put into operation, giving tour players and owners from around the world on an equal say in the operation of the new competition system. ATP now has been the development of men's professional tennis ball tournament's governing body and is responsible for the international tennis ball Federation (InternationalTennis Federation, ITF), the International Women's tennis ball Association (Women's Tennis Association, WTA) and other international organizations to coordinate tennis ball . After 4