EXO Series Spark Plug Boots are designed to withstand extreme racing and high heat environments. The outer Exoskeleton stainless mesh prevents direct contact with the Dual layer Silica boot underneath. This combination of Silica/Air Gap and Stainless steel provides outstanding heat protection for your plug boots and wires. Available in 2, 4 and 8 packs so you can protect trouble areas or your complete wire set.