The FitBALL Mini Exercise Ball brings a whole new dimension to core and muscle training. This 9in ball adds a level of instability and can be used in Pilates, Yoga and fitness training. Place the FitBALL Mini under your lower back when performing crunches for a challenging workout. The soft rubber surface provides comfort and requires inflation. Deflate the FitBALL Mini and use as a prop under your head, neck, feet, etc.