Here is another smart gadget that helps you work on developing wrist strength. The 75PAI Gyro Ball combines with your phone to show time, laps, and a lot more. It can increase the strength of your fingers, wrists, hands, and forearms.
The 75PAI Gyro Ball has a zinc-alloy core and a transparent protective cover. It can start automatically. You just have to push the core in the direction of the arrow. The battery lasts up to half a year.