| 摘要 |
<p>PURPOSE: To adjust elastic force, extend or suppress the flight distance of a ball, allow a practice not only at a wide place but also at a narrow place by forming an elastic spring on a ball hitting face, or forming a wound spring or an elastic material on the back of the hitting face. CONSTITUTION: An elastic spring 1 is formed on a ball hitting face. A wound spring 2 or an elastic material is fitted on the back of the elastic spring 1 of the ball hitting face, and the strength is adjusted by a set screw 3.</p> |
