Get those biceps looking good for the summer & strengthen your arms & wrists with the Signature Powerball. It has a sapphire & white light & neon rotor that revolves inside a subtly smoked shell. This is a serious design classic. Put the rotor in action & the ball will come alive with Gyroscopic force. It features a top speed that exceeds 16, 000rpm, creating over 40lbs of resistance, resulting in a serious workout! There is a built-in digital computer on the outside allowing you complete control over how fast (or perhaps slow!) you wish to operate the ball. It also holds data like your highest speed. Get those biceps pumping in Signature Powerball style!