| 摘要 |
A tennis training or exercising device in which a depressurized tennis ball is provided with an opening communicating with the interior and exterior of the ball, to allow air to pass freely from the interior of the ball when the latter is struck. A flexible cord is connected to the ball and has one end connected to the ceiling through a pressure-sensitive hook, and the other end connected to a standing weight which is placed on the floor. The passage of air from the interior of the ball to the exterior thereof, permits the ball to oscillate in a controlled manner after being struck. A counter arrangement at the bottom of the cord, will count only correctly applied strokes to the ball.
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