... , middle-aged, the elderly etc cyclone changing the ball is a new kind of sport toys, similar to the play badminton, but ... ball of play:Whirlwind changeful ball could single play, double play, also many teams play.Single play: challenges casts accurate, high and fly magic ... .Double play: see who threw a prospective, good catch.3-6 team play, each in 8 * 10m range of venue ...