Material: The Baoding Balls is made of iron with plated chrome, durable and sturdy. Smooth surface is safe to use. Finger Exercise: Two or more baoding balls are rotated repetitively in the hand to improve manual dexterity and strength. Stress Relief: Beneficial to the brain, playing health ball, you can make people's thoughts focused on the hands, eliminate all kinds of distractions. Health Care: In addition to relieving stress, health balls or baoding balls are known to improve joints, blood circulation, sleep patterns and memory. Hand Massage: By running the ball with the fingers, the moving ball will stimulate the acupoints of the fingers and palms, which can play a role of exercise.