CanDo Square Ball RebounderCanDo Square Ball Rebounder The CanDo Square Ball Rebounder, which includes a built in rack, is ideal for physical therapy, rehabilitation and training sessions to improve strength, reflexes and coordination. The rebounder and balls are a fun way to improve conditioning, hand eye coordination and lateral movements. The rebounding area is a generous 39" (diagonally) attached by springs to a 39. 5" x 39. 5" frame that tops out at less than 4. 5' tall.