Spark Plug Wires, Super Conductor, Spiral Core, 8.5mm, Red, Chevy, GMC, LS Series Truck, 4.8/5.3/6.0L, Set. A tough, 8.5mm synthetic/silicone jacket over an extra-heavy glass braid and dielectric insulator keeps the current guided to the plugs. Underneath the high-temperature boots, dual crimp stainless steel terminals feature snap-locks to ensure a secure fit. Each set comes with clip-on cylinder markers for easy identification. MSD's 8.5mm Super Conductor wire sets are available in custom or universal-fit applications, assembled or not, with a variety of terminal and boot end options.