The size of the Powerball is as a baseball, when Powerball speeds up to 10,000rpm, the forces become much stronger. And if it is at a full tilt it creates a gargantuan pressure of around 40lbs which is revolving around 230 to 250 rounds per second which is too hard to resist. This product does not make use of batteries or any motor, only gyroscopic power. There are different Powerball available in the market having variety in led, colors, and metals. It is a fantastic product for rock climbers, water skiers, bowlers, drummers, tennis, squash, and golf players to strengthen their hand and arm.