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A cricket ball is a hard, solid ball used to play cricket. A cricket ball consists of cork covered by leather, and manufacture is regulated by cricket law at first class level. The manipulation of a cricket ball, through employment of its various physical properties, is the staple component of bowling and dismissing batsmen. Movement in the air, and off the ground, is influenced by the condition of the ball, the efforts of the bowler and the pitch, while working on the cricket ball to obtain an optimum condition is a key role of the fielding side. The cricket ball is the principal manner through which the batsman scores runs, by manipulating the ball into a position where it would be safe to take a run, or by directing the ball through or over the boundary. In Test cricket, professional domestic games that spread over a multitude of days, and almost the entirety of amateur cricket, the traditional red cricket ball is normally used. In many one day cricket matches, a white ball is used instead in order to remain visible under floodlights, and since 2010, pink has been introduced to contrast with players' white clothing and for improved night visibility.〔("Does the white ball behave differently?" ) BBC Sport. Retrieved 23 November 2013.〕 Training balls of white, red and pink are also common, and windballs and tennis balls in a cricket motif can be used for training or informal cricket matches. During cricket matches, the quality of the ball changes to a point where it is no longer usable, and during this decline its properties alter and thus influence the match. Altering the state of the cricket ball outside the permitted manners designated in the rules of cricket is prohibited during a match, and so-called 'ball tampering' has resulted in numerous controversies. Cricket balls, having a mass between 155.9 and 163.0 grams, are known for their hardness and for the risk of injury involved when using them. The danger of cricket balls was a key motivator for the introduction of protective equipment. Injuries due to cricket balls occur, and fatalities have been attributed to cricket balls. The nature of the cricket ball slightly varies with its manufacturer. White Kookaburra balls are used in One Day Internationals and T20Is, while red Kookaburras are used in Tests played in most of the 10 Test-playing nations,〔(【引用サイトリンク】title=India opens door to Kookaburra balls in Tests )〕 the exceptions being the West Indies and England, who use Dukes, and India, who use SG balls.〔(【引用サイトリンク】title=India opens door to Kookaburra balls in Tests )〕 ==Manufacture== British Standard BS 5993 specifies the construction details, dimensions, quality and performance of cricket balls. A cricket ball is made with a core of cork, which is layered with tightly wound string, and covered by a leather case with a slightly raised sewn seam. In a top-quality ball suitable for the highest levels of competition, the covering is constructed of four pieces of leather shaped similar to the peel of a quartered orange, but one hemisphere is rotated by 90 degrees with respect to the other. The "equator" of the ball is stitched with string to form the ball's prominent seam, with six rows of stitches. The remaining two joins between the leather pieces are stitched internally. Lower-quality balls with a 2-piece covering are also popular for practice and lower-level competition due to their lower cost. For men's cricket, the ball must weigh between 5 1/2 and 5 3/4 ounces (155.9 and 163.0 g) and measure between 8 13/16 and 9 in (224 and 229 mm) in circumference. In women's cricket the ball must weigh from 4 15/16 ounces (140 g) to 5 5/16 ounces (151 g) and measure between 8 1/4 and 8 7/8 in (210 and 225 mm) in circumference. A plastic cricket ball (known as a "Kwik cricket ball") is often used in matches for players who are younger than 9 years old. Matches for 10- to 13-year-olds are played with a ball weighing between 4 11/16 and 5 1/16 ounces (132.9 and 143.5 g). The ball for 10- to 13-year-old games must measure between 8 and 8 7/8 in (205 and 225 mm). Any match for 14 year olds and above which is not a men's match is still played with a full-sized men's cricket ball.〔(【引用サイトリンク】title=ECB recommendations for junior cricket )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cricket ball」の詳細全文を読む スポンサード リンク
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