When exercising, hold two cloisonne fitness balls in the palm of your hand, flex and stretch them with five fingers in turn, so that the two balls circle each other, and the rotation direction is divided into positive and negative directions, so that all joints of your hand are moving. With the flexion and extension of fingers, forearm muscles can contract and relax rhythmically. You can choose a small model at the beginning of training. After you are proficient, you can gradually choose a larger model. You can move alternately with your hands, or you can spin three or four balls at the same time to play various tricks.