Made From Cast Aluminum With Natural FinishUtilizing the durable and dependable High Energy Ignition (HEI) system pioneered by GM, these units offer calibrated advance curves that are optimized for maximum combustion efficiency and for the elimination of detonation damage. Durable onepiece design: the coil and module are mounted internally for easy one wire hook up. Each unit includes a high power coil, a premium hi dielectric red cap with brass terminals, and a low saturation ignition module.