These 9mm wires feature a spiral - wound suppression core for low resistance and minimum spark loss. They have tough silicone insulation to withstand high temperatures and voltage loss for minimum crossfire, and are highly resistant to fuels, oils, and solvents. Other features include 45 degree plug boots (most applications), stainless steel distributor cap terminals, and a coil wire (if applicable). The wires are numbered for each cylinder and have the 'Ford Racing' script on them.