The Accel Performance 300+ ThunderSport Ferro-Spiral Spark Plug Wire Set features high-density, high-temperature and high-durometer silicone insulation provides greater dielectric strength. The oversized 8mm wire features a double silicone construction rated at over 550 degrees Fehrenheit and 60k V-rated. The high gloss red silicone wire jacket resists heat extremes, petrochemicals, ozone and has moisture for greater durability and longer life. It provides excellent energy delivery to the spark plugs, while providing the highest level of Radio Frequency Interference / Electromagnetic Interference suppression. The Kevlar stranded inner core and fiberglass braiding adds greater pull strength and terminal retention.