【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. 【AUTO START DESIGN】 The second generation of new products, 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, Carpal Tunnel Syndrome, RSI or Tendonitis. 【MAKE ERCISE & ADD FUN】 Novelty design with LED lights, which is fun to see how fast you can get it spinning. Cool LED lights inside will light up while spinning. Rehabilitates sore muscles, Kill the time & Add fun ! 【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. Impact Resistant structure with Military-grade plastic shell. The LED light is not powered by batteries. It's battery free. No need to worry about power running out.