This Blue Massage Ball is the largest in a range of five, measuring 100mm (4\") in diameter.Extremely robust this massage ball provides a multidimensional product whilst remaining highly cost-effective. Ideal for use within any environment this massage ball can be used for a self-massage or with assistance to treat back pain, improve blood flow, stimulate muscles and ease tension. For a firm massage, you simply apply the ball to skin and rotate in a circular motion. Other coloured and sized Massage Balls are also available in this section of the shop.