Tennis Balls

Tennis balls are of hollow rubber with a felt coating. Traditionally white, the predominant color was gradually changed to Optic Yellow in the latter part of the 20th century to allow for improved visibility. Tennis balls must conform to certain criteria for size, weight, deformation, and bounce criteria to be approved for regulation play. The International Tennis Federation (ITF) defines the official diameter as 65.41-68.58 mm (2.575-2.700 inches). Balls must weigh between 56.0 g and 59.4 g (1.975-2.095 ounces).[36] Miscellaneous Advanced players improve their performance through a number of accoutrements. Vibration dampers may be interlaced in the proximal part of the string array for improved feel. Racket handles may be customized with absorbent or rubber-like materials to improve the players' grip. Players often use sweat bands on their wrists to keep their hands dry as well. Finally, although the game can be played in a variety of shoes, specialized tennis shoes have wide, flat soles for stability and a built-up front structure to avoid excess wear.

Another, however informal, tennis format is called Canadian doubles. This involves three players, with one person playing a doubles team. The single player gets to utilize the alleys normally reserved only for a doubles team. Conversely, the doubles team does not use the alleys when executing a shot. The scoring is the same as a regular game. This format is not sanctioned by any official body. "Australian doubles", another informal and unsanctioned form of tennis, is played with similar rules to the Canadian doubles style, only in this version, players rotate court position after each game. As such, each player plays doubles and singles over the course of a match, with the singles player always serving. Scoring styles vary, but one popular method is to assign a value of 2 points to each game, with the server taking both points if he or she holds serve and the doubles team each taking one if they break serve. Wheelchair tennis can be played by able-bodied players as well as people who require a wheelchair for mobility. An extra bounce is permitted. This rule makes it possible to have mixed wheelchair and able-bodied matches. It is possible for a doubles team to consist of a wheelchair player and an able-bodied player (referred to as "one-up, one-down"), or for a wheelchair player to play against an able-bodied player. In such cases, the extra bounce is permitted for the wheelchair users only.