HKS Mi-Series Super Fire Racing Spark Plug - HKS M45iL - Grade 9 Note - Price is for 1 single spark plug HKS Mi-Series Long Reach Super Fire Racing spark plugs are high performance Iridium plugs designed to handle advanced levels of tuning and provide Improved ignition performance, durability and anti-carbon build-up.HKS Mi Series Spark Plug Features: 0.6mm Iridium Alloy Centre Electrode. Iridium Alloy Centre Electrode reduces voltage requirement as well as improving ignition performance and durability. Outer Electrode with Platinum Chip. The Outer Electrode incorporates a square platinum chip which improves durability, and when combined with the iridium centre electrode boosts ignition performance. Short Type Outer Electrode (Anti-Vibration). The outer electrode has been shortened and engineered with the ideal shape to decrease weight for resistance against vibration. This anti-vibration design improves longevity of the outer electrode. Thermal Edge: After long idling or various combustion conditions carbon buildup can occur causing misfires. The Thermal Edge of the ceramic insulator will discharge to help decrease carbon deposits. Spark Support Gap: Discharges will occur in the Spark Support Gap (space between the tip of insulator and the base of the outer electrode) to help prevent carbon buildup. Long Reach Heat Range: 9 Fensport Tip: How to choose a sparkplug grade. (Guide Only)For NA Cars: Grade 7 is usually one step colder than standard , grade 8 can be used in high heat / high compression cars.For Turbo Cars:Grade 7 mild upgrades usually 1.2 bar boost, Grade 8 above 1.2bar, Grade 9 above 1.6Nitrous Oxide:Usually a colder grade plug is often used when using nitrous oxide.If you need help please call for details