The tower assembly is molded of durable alkyd material due to its high dielectric characteristics while wide spaced brass primary terminals prevent the possibility of spark. Each Blaster Coil can be used with a stock ignition, Blaster Ignition, MSD 5, 6 or 7 Ignition Control. Most late model vehicles with electronic ignitions do not require a ballast resistor, check your ignition and manufacturers specifications to determine if a ballast is required in your application. Mallory Unilite applications also require the ballast resistor.