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.GOOD FOR HEALTHThe 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.STRENGTHEN YOUR WRIST AND FORRARMThanks for gyroscope force, this small ball can generate huge power and do more workout than you think it could be for your forearm.This gyro ball correspond to 50 dumbbells of different weights.Control the speed and power with your hand, 10,000 rotational speed per minute could generate about 35 lb weight.NO BATTERIES Impact Resistant structure with Military-grade plastic shell. The LED light is not powered by batteries. Its battery free. No need to worry about power running out.Great giftIts a great gift for people who love sport or work all day in the office.Its quite useful for for strength and rehab your wrist and forearm. Its also a great gift for musician like guitar player, piano player for strengthen their finger strength.