The Phoenix Fitness Spiky Massage Ball Set contains three 3 spiky massage balls of varying sizes for use in a deep tissue massage.The spiky massage balls can gently relieve muscle knots by rolling over the affected area in a repetitive motion. They can improve blood circulation by applying pressure through the congested areas, massages can also flush lactic acid from muscles and organs to lower blood pressure and improve body function. The Phoenix Fitness Spiky Massage Balls are also excellent for adults and children with autism or a sensory processing disorder as they are brightly coloured and physically stimulating to touch, squeeze and roll across the floor with your hands or body.