| 摘要 |
<p>A baseball or softball bat capable of increasing the hit distance of a ball and reducing the manufacturing cost can be obtained. A baseball or softball bat (1) including a hitting portion (2), a taper portion (3), and a grip portion (4) has a tubular member (6a, 6b) which includes an outer circumference plane (25) extending from the hitting portion (2) to the grip portion (4) and an inner circumference plane (26) located inside the outer circumference plane (25) and extending from the hitting portion (2) to the grip portion (4), and a metal tubular member (8) which is placed between the outer circumference plane (25) and the inner circumference plane (26) at least in the hitting portion (2), the metal tubular member (8) having a weak boundary layer (7) formed on its surface.</p> |
