1. Make Arm Great Again. Strengthen fingers, wrists, hands, forearms, shoulders, and bicep, etc. It also can be beneficial in promoting co-ordination and blood circulation.
2. This certainly requires some fine motor skills in order to use it. The dominant hand/arm was easily able to keep the gyro ball going, that it will help refine you're fine motor skills in that non-dominant hand/arm.
3. Small, compact and transportable, you can take anywhere. Simple to start with a pull-string, all you need do is to increase the speed by making a rotational wrist movement and to keep in sync with the spinning of the ball.
4. The unit did not have any weird vibration to it. Also having the silicone grip section is very nice as it helps with the gyroball not coming loose from your hand. You can attach it to a wrist strap if you are really concerned about the gyroball flying away.