Extended tip - helps prevent fouling at low engine speeds and self-cleaning at high engine speeds
Extra-extended tip - used in specially designed engines to project farther into the combustion chamber
Single platinum tip - used for both conventional and coil-on-plug ignition systems, provides service intervals from 60,000 to 100,000 miles
Finewire platinum tip - top quality plugs that use more platinum to reduce fouling firing voltage and provide even longer service intervals than other platinum offerings
Nickel-alloy - these plugs feature electrodes engineered for extended life without platinum enhancements