Vex robotics 406 4577 gear racer by hexbug da vinci auto cart vex 406 4577 p children can experience the fun of building their own speedy robot inspired cars with vex reg robotics gear racers by hexbug reg p p gear racers teach you about how machines convert potential energy into kinetic energy while the multiple gear ratios teach you about the fundamental principles behind speed and torque p p vex reg robotics gear racers include multiple gear sets rubber bands wheels and all