Because it is very difficult to catch the rainbow ball. According to relevant information, rainbow ball is a new type of leisure fitness prop. The rainbow ball mentioned by volleyball lovers generally refers to the transition ball with obvious curvature. Generally, when the cooperation between attack and passing is not ideal, the attacker can only handle the ball over the net, so the rainbow ball came into being. Generally speaking, when the attacker reaches the hitting point, the ball doesn't have a good power point to cross the net, or if it can't cross the block, it can only be handled by hanging the arc and crossing the net.