| 摘要 |
A sports training ball 1 comprises a high drag coefficient component 2 and a low drag coefficient component 4 which together give the ball an inherent swing capability when it is projected through the air. The high and low coefficients of drag can be obtained by surface indents 3, protuberances, bristles and other means. The ball can be used for training in cricket, golf, tennis, football, baseball. The ball 1 can also be provided with a circumferential seam 5.
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