1.Size and weight: 17*13.6*3.5cm, 148g. 2.Material: copper+ABS. 3.Function: satisfying the requirements of finger training of various musical instruments. Fully improve the accuracy, endurance, and explosiveness of fingers, palms, wrists, and arms in sports and other work, and fully reduce the vulnerability of fingers and wrist joints. Improve the general physical fitness, because the finger, palm, wrist, and forearm muscle groups are the soul muscles of the commanders body movement system. Maintain, develop, and strengthen to ensure all competitive strengths. 4.Left-hand exercise to develop the right brain, right hand exercise to develop the left brain, both hands at the same time without synchronized exercise to improve the coordination of left and right brain.