| 摘要 |
The tennis ball provides a medium physical property between the regulation ball and the softball so that it bounds less than the regulation ball but yet better than the softball for tennis beginners to play easier. The ball is made of 100% natural rubber in the wall thickness of 2.3-2.7mm with felt coating of 2.0-2.5mm thickness to have 37-40g weight and 0 psi on the inside.
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