| 摘要 |
PROBLEM TO BE SOLVED: To overcome the disadvantage that a closure is inadvertently dislocated and jumped out during the game by providing an air insert part and a closure with a star-like groove to increase the contact frictional area between them in a closure for a game ball used for a beach ball or the like. SOLUTION: A closure for a game ball used in beach ball or the like is connected to an air insert part by a belt 3. A through hole having a valve 5 made by cutting a part of the bottom is provided at the center of the air insert part, and the air is injected from the outside through the through hole to inflate a ball. A star-like groove 8 is longitudinally cut in the inside of the air insert part, a star-like groove 8' is longitudinally cut on the outside of the closure corresponding to the groove 8', and a hollow part is provided in the interior. Accordingly, when the closure is inserted in the air insert part, the star-like grooves 8 and 8' of both members closely adhere to each other to increase the contact frictional area, so that the closure can be surely prevented from being inadvertently separated from the air insert part.
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