Speedmaster Ignition Wires are designed to produce the highest spark energy transfer, highest EMI/RFI suppression and the highest horsepower gain. Speedmaster's Ignition Wires contain a high-temperature silicone insulator outer layer for extra insulation that extends spark plug wire life against exhaust header heat, chaffing and contaminants. These ignition wires come complete with a high dielectric strength insulator, heavy glass braid, heavy-duty black silicone jackets and high-temperature black boots.