NGK builds two types of iridium spark plugs: OE Iridium and Iridium IX®. Every plug in the Laser Series was designed for an OEM application. All dual precious metal plugs are designed to provide maximum longevity. For the OE Iridium series, dual precious metal means iridium on the center tip and platinum on the ground electrode. Some of these plugs have special resistors or multiple ground electrodes, depending on the original equipment requirements.The Iridium IX® spark plugs are a single precious metal aftermarket performance plug. They are a great option for modified engines, and where recommended, are appropriate replacements for OEM spark plugs. Iridium IX® plugs are an excellent upgrade from standard nickel plugs. The Iridium IX® plugs are offered in various heat ranges and sizes to fit most automotive and non-automotive applications.

These two plugs perform similarly, due to their fine-wire tip design, but the service interval is different; the Laser Series are typically designed to last 80 to 100 thousand miles, where as the Iridium IX® spark plugs are designed to last 40 to 50 thousand miles.