Designed with Sprint cars in mind, the Pro-Mag 12LT is almost 30% lighter than the original Pro-Mag, but still produces the same incredible power. The compact housing sits an inch lower for improved clearance of the fuel injection, and it features a band clamp mount for easier timing adjustments. MSD has also designed a cap and rotor specifically for the 12LT series. The cap is injection molded from DuPont Rynite material, which possesses high dielectric properties and incredible strength. The innovative rotor design clamps to the shaft with a retaining bolt assembly and is also molded from Rynite. Note: A 12LT Generator cannot be upgraded to a 20 Amp Pro-Mag.