NGK Iridium IX Spark Plug Box of 4 (WR5IX)

The fine iridium center electrode on these NGK Iridium IX spark plugs has a melting point six times harder than platinum, making it well-suited for today's higher-temperature engines. This durable construction helps ensure a consistent spark, which translates to improved starting, smoother idling, and better throttle response. These plugs are a good choice for modified or high-performance applications, or simply as an upgrade over standard nickel alloy plugs.

NGK uses a trivalent metal plating on the exterior of the plug, which helps resist corrosion and makes them easier to remove later on. The tapered cut on the ground electrode is another design choice aimed at improving ignitability. This set includes four spark plugs, enough for most common 4-cylinder engines, and fits a wide range of vehicles from the 1950s through the mid-1990s, including many Ford and Dodge models.