Add a fun element to your workout with 66fit rubber reaction ball! Our ultra-fast unpredictable reaction balls allow you to hone your reaction times, improve hand/eye coordination and sharpen your reflexes all whilst having fun! Simply throw the ball on the floor or against a wall, watch it bounce and react to improve your speed, agility and catching skills. 66fit Reaction Balls are also an ideal choice to target your sense of balance and proprioception. Small - 7cm or Large - 10cm.