Crank Trigger Wheel Kit Flying Magnet Bbf 7.25 In. Big Block Ford 429-460Ci Use With 6/7/8 Series Red MSD IgnitionMost crank triggers have a wheel, with steel studs sticking out, bolted to the harmonic balancer. As the crankshaft turns, the studs pass by a stationary magnetic pick up, triggering the ignition. This pick up can be triggered by other bolts, debris, or even vibrations which will cause a loss of power or engine damage. The MSD Flying Magnet Crank Trigger uses four magnets secured in the aluminum trigger wheel that pass by a stationary non magnetic