What&<br> 39;s the ball used for? - Baoding ball is traditional folk fitness equipment, designed to do hand exercise, make your thoughts focused on the hand,strengthen your hands and keep them flexible.Premium Natural Material - This health ball is made of beautiful natural black obsidian gemstone, the traditional cutting process make it smooth and shiny.Good for all - As a hand exercise tool, this Baoding Ball is good for adults, children and people who need surgery rehabilitation, enhance blood circulation and blood flow by controlling with the pressure of your hand.Different Sizes - 1.57 in is for small to average hands. 2 in is for larger hands or more skilled users.A Great Gift - Baoding ball originated in the city of Baoding during the Ming Dynasty in China, it&<br> 39;s a good personal collection and a beautiful gift.Baoding ball is traditional folk fitness equipment, it can enhance blood circulation and blood flow by controlling with the pressure of your hand, strengthen your hands and keep them flexible, fine motor movement exercises the brain keeping it sharp. How to use? Hold 2 balls in one hand and rotate them in circles in the palm of your hand. Relying on five fingers flexion and extension, so that the two balls circled with each other. Material: Beautiful natural black obsidian gemstone Size: 1.57 diameter, 2 diameter Color: Shiny Black Package Included: 2 Pcs Baoding Ball