| 摘要 |
A hollow aluminum bat including a tubular handle portion at one end thereof merging into a tubular barrel at the other end with the barrel having a constant external and internal diameter and a closure end cap is provided with grooves formed in the internal surface of the barrel which reduces the weight of the barrel to enable the barrel to be made with a larger constant diameter throughout its length. The grooves maintain the impact characteristics of the barrel with a ball. The grooves may include a continuous spiral groove having a plurality of closely associated convolutions, a plurality of longitudinally spaced, circumferential grooves, or a plurality of circumferentially spaced longitudinal grooves formed in the interior surface of the constant diameter barrel and oriented over substantially the full length of the accepted hitting zone defined by the barrel.
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