NGK Laser Iridium Spark Plug Box of 4 (SILMAR9B9)NGK Laser Iridium High Ignitability spark plugs offer the best combination of performance and longevity. Engineered specifically for OE applications, Laser Iridium High Ignitability spark plugs are tested to the highest standards to ensure quality and durability. Iridium tipped center electrode provides durability six times harder than platinum. NGKs high grade pure alumina ceramic and 98 percent pure copper core prevents the spark plug from