【Performance Digital LCD counter】No battery and self-powered digital display with blue background light,can track your exercise information,including real-time RPM,real-time force,total time and calorie calculator. 【ALL METAL MATERIAL】Made of heavyweight metal, aluminum alloy shell and steel rotor,It weighs twice as much as plastic.to provide a powerful hand & forearm exerciser which could be equivalent to 50 lbs fitness of other equipment. The metal design is enhances for control, vibration free, and stability. 【AUTO START DESIGN】 The second generation of new products gyro ball, you only need to push the core in the direction of the arrow, start by the internal spring, no rope. 【GOOD FOR HEALTH】The wrist ball can assist body to restore to health. There is a strong reaction at high speed, the faster the speed, the greater the power, and the effect of exercise. At the lower speed, it is also a very effective tool release soothe , recuperate sore and damaged limbs, or help reduce the inflammation caused by Arthritis, RSI or Tendonitis. 【HIGH QUALITY】 The unit did not have any weird vibration to it. Also having the silicone grip section is very nice as it helps with the gyro ball not coming loose from your hand. At the same time ,turn your palm down slowly rotating your wrist br to get the power to maintain the existing gyro ball or higher than the starting speed. br br Step3: When you turn the core speed up gradually , you will feel the same synchronous growing reacting power br on your wrist and your arm with the rotating gyroscope. br when you reduce the circle diameter your wrist draw , the speed will be up. the smaller the circle diameter, the faster br the rotation of the core will be meanwhile ,the more difficult the wrist will feel to move. br br Application range of gyro ball: br br Muscle training from wrist to elbow: wrists, forearms, upper arms, biceps, triceps and shoulders, improve br arm strength and flexibility, prevent tendonitis. br br Suitable for the elderly, nursing, treatment, rehabilitation personnel: In fact, gyro ball does not put too much load br on the muscles, improves blood circulation in the wrist and prevents nerve damage. br br Eliminate work stress, gyro ball's led flash and vibration make white-collar workers relax.