The original Z-Ball is BACK and BETTER! Z-Ball is now a patented exclusive from Oncourt Offcourt and is 40% bigger for easier handling and catching. The 7-knob design creates the same unpredictable bounces, but eliminates the impossible bounces of the previous ball. The 2-color design increases visibility substantially. Use the blue and yellow ball on gym floors, and the orange and yellow ball on darker surfaces. Ideal for beginning to intermediate athletes ages 7 - 13. Color: Yellow