The Gymnic Soft Gym OverBall exercise ball is a very versatile 23 cm. ball which is soft on impact. It is made of soft PVC foam that is easy to grip and provides resistance for a variety of isometric exercises.These softgym balls can be thrown at full strength. Suitable for Pilates work, children and the elderly. If not fully inflated they can also be used as a lumbar support, dynamic seating or unstable platform. This Soft Gym Ball adds concentration and energy to your workouts. OverBalls are strong and easy to grasp. Inflates to 9". Gymnic OverBall exercise balls is terrific for Pilates and can also be used for rolling massage and as a soft prop underneath various parts of the body. These fine exercise balls are ideal for isometric exercises, leg work, a great aid for performing proper abdominals, and so much more.