Our C7 Corvette performance spark plug wire sets begin with a heat shielded Magnacor wire. Magnecor's exclusive 2.5mm high capacity Metallic Inductance EMI Suppressed conductor consists of a stainless steel wire precisely wound at 200 turns per inch over a ferromagnetic core. The insulating jacket is made entirely of Magnecor's exclusive TC-1500-HS high strength aerospace grade silicone rubber, and its single layer construction will prolong the jacket's insulating ability by conducting extreme heat away from hot-spots that occur near over-the-limit heat sources.The protection provided from the heat shield guarantees that this will be the last set of spark plug wires you will ever have to replace from header burn. The 8.5mm jacket has a service heat resistance of 600 degrees F (320 degrees C) and up to 1,000 degrees F (540 degrees C) for a short burst of 3 minutes. Even if limits are exceeded, the silicone rubber will retain its insulating ability until wires are removed from engine. In addition, Zip’s Corvette wires include 6” long fire boots, which enable the wires to withstand 1200 degrees of direct heat