Some of the boxes do not contain instructions and information, so I am including it here: "Chinese iron balls have long been famed as on of the 'three treasures' of Baoding, China. First produced during the Ming Dynasty (1363-1644), iron balls have often been improved through the ages by skilled Chinese handicraftsmen. Originally, these balls were simply walnuts. Yes walnuts. Then they were facsimilated by creating simple, solid, cylindrical objects. Later, handicraftsmen began designing hollow balls and inserting sounding plates that produce high and low tones when used. The balls we have today are lighter and easier to handle, and the musical tones contribute to the relaxation process that results from exercising with them. The tones should correspond to the tones of the five elements. DIRECTIONS: The health balls are placed in one's hand and rotated in either a clockwise or counter-clockwise direction. This exercise will keep all of the 'points' in one's hands in constant motion, with the muscles in one's fingers and forearms contracting and relaxing harmoniously. Beginners should select balls of a smaller size and then, over time, increase ball size as one's proficiency improves. Ultimately, one can exercise both hands alternately or simultaneously and may even choose to use three or four balls in one hand - or graduate to the larger Stone Balls.