Out door game e.g. tennis, play enabling device, has counterweight sliding freely in hollow tube and connected to ball via rubber band whose tie point is movable along vertical axis, and stopper to prevent counterweight from leaving tube

摘要

The device has a ballasted base (1) that maintains a hollow tube (2) vertical in which a counterweight (3) slides freely. The counterweight is connected to a ball (4) through a rubber band (5) and a short nylon wire (6), where the tie point of the rubber band is movable along a vertical axis. The wire acts as a junction between the rubber band and the ball. A stopper (7) prevents the counterweight from leaving the tube.