The Seller Say:Artificial Tiger Eye Stone Baoding balls are raw natural stone sphere, small enough to hold in one hand.They are also known as Chinese exercise balls, health balls,hand balls, meditation balls, Chinese medicine balls.Baoding balls are Used by rotating two or more balls repeatedly in the hand. Intended to improve finger dexterity, relax the hand, or aid in the recovery of muscle strength and motor skills after surgery, Baoding balls work similarly to Western stress balls.Material:Crystal jade stone.Why choose RCSTONE Baoding Balls?①Improve the finger dexterity and hand strength.Watch some videos online to learn different tricks - each trick works out different muscles in hands.For softball pitching students, karate and jujitsu Students, this help them All around training.Doing the hand exercises recommended in Tai Chi or QiGong class.②It is good for relieving arthritis and maintaining manual dexterity.The hands are getting arthritis and stiff from prolonged keyboarding. With arthritis the hands get sore, reduce stress when used as alternative medicine to stimulate the acupuncture points on the hand. and keep them from cramping.Handling it will strengthen hands for physical therapy.Use it as a massage ball to rub someone's back and can also be used with the feet. ③ Good for hand-eye coordination, concentration, inner peace.These balls (keep them in the fridge) rolled around the face reduce any other puffiness.Feels so nice on the skin when used to massage.The spheres are perfectly round.Each ball diameter (about) 1.57 in.There is a slight variance in size, which is understandable. The variance is almost unnoticeable and it doesn't affect the rolling in the hand. Since the material is Artificial Tiger Eye Stone, please do not roll down from a height.