Organic and natural jade Baoding balls have been polished to perfection, and are 5cm in size and approximately 350g per pair. Stimulating the hand's metacarpal bones will relax the central nervous system and improve mental alertness. Exercise with the fitness balls flexes and stretches fingers, palms, and wrists, helping to reduce numbness and tremor in elderly people. Mental focus and relaxation of the brain comes from playing the balls. Variations in size and color may be present.