| 摘要 |
A highly specific type of hooked materials, when applied to the shoulder of a tennis racquet, have been found to tangentially hook onto the nap of a tennis ball and allow the ball to be lifted from the court. Hooked materials characterized as comprising a series of heat-treated nylon monofilament hooks in a rowed relationship (300/inch<2>) of an average diameter of 8.5 mil, 1.91 mm mean height, 1.13 mm mean width and 0.71 mm mean hook depth are particularly effective for retrieving all common types of tennis balls.
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