Pro Spark Plug WiresPrecut and have the plug/coil boots and terminals already installedBoots and wires are made from extra-high-temperature silicon, which gives protection up to 600°FSpiro-Pro core provides up to 10 times the conductivity of a standard carbon-core wireLow resistance means they run cooler and last three to four times longer than carbon-core wiresMade in the U.S.A.Material: Silicone Units: Pair Wire Diameter: 8 mm Product Name: Spark Plug Wire Color/Finish: Black