PerTronix 708104 Flame-Thrower Black Custom Fit Spark Plug Wire for 8 Cylinder Ford Two current paths for reliability and redundancy -Primary path: Spiral wound stainless steel alloy -Secondary path: Carbon impregnated fiberglass center core Low 500 ohm per foot resistance 7mm Silicone jacket to resist high temperatures, moisture, oil and chemicals EPDM (Ethylene Propylene Diene Methylene) inner insulation for superior heat resistance and prevention of arcing and voltage leaks Fiberglass reinforcing braid for added strength and flexibility