Ceramic wire wound ballast resistor as used in some ignition circuitswith a ballast ignition coil. When the ignition key is turned to “start”, the resistor is shorted out, giving the coil the full 12 volts and therefor a much hotter spark. When the ignition key is released the current has to flow through the resistor to give the coil its working voltage. An engine that starts readily but stops when the key is released, often has a defective resistor. (Not Lucas branded)