The product is composed of a base, a panel, flat parabolic guide, ball groove, leveling bolt, flat throwing, hammer, paper clips, flat plate column, power line etc.. Base size : 350 x 130 x 12 mm, flat parabolic guide is made of aluminum alloy profile, rail width 20mm and guide for bearing flat ball, and flat ball position height can be adjusted, and make the ball thrown; wiring groove height position can be adjusted freely; flat ball diameter 16mm。