Pack of 12 speed rings. Place on the ground and work on footwork. Tap your toes into each ring consecutively for as little time as possible to train footwork and work on fast-twitch leg muscles. Great endurance and muscle-toning workout. Perfect training for soccer, football, basketball, and practically all other sports. The outside diameter measures 12" and the inside opening diameter is 11". Pack of 12 - 4 red, 4 blue, 4 yellow. By Trademark Innovations.