Accel 8.8mm Suppression Core Spark Plug Wire Set For Harley Features: Accel's ready to install custom fit wire sets provide improved performance both electrically and mechanically Extra-thick silicone jacket covers strong fiberglass braid that covers another layer of silicone that covers high capacity conductors At the plug end, positive stainless steel terminals lock onto the spark plug to assure a secure installation High dielectric strength silicone spark plug boots provide excellent insulation, preventing arcing to the cylinder heads