This is a must-have, add-on for Dynaflex Powerball upgrading the ball to the ultimate performance machine. Just snap it into your Dynaflex Powerball and begin recording your speeds. The Dynaflex Speed Meter displays your RPM in real time and records your high scores. It also calculates the maximum numbers of the revolutions. A great tool to precisely keep track of your progress! Have fun with your friends or coworkers by engaging in competitions to see who can generate the fastest speeds!