... students, middle-aged, the elderly etc. Whirlwind changeful ball is a new kind of sport toys, similar to the playbadminton, but have ... recreation and fitness at an organic whole.Whirlwind changeful ball of play:Whirlwind changeful ball could single play, double play, also many teams ... .3. 3-6 team play, each in 8 * 10m range of venue for the stadium, between5-8m distance, mutual cast on ...