Watch your marbles take off like a shot with the “GraviTrax Magnetic Cannon”! Launch the marble through your run by adding the Cannon. The high-powered magnet gives the marble speed to help extend your run by boosting it up inclines and down tracks. This accessory also includes 3 additional marbles. GraviTrax Starter-Set required. Comes complete with 1 Magnetic Cannon, 3 colored marbles and instructions.