Iridium centre electrode (0.6mm diameter). Better ignition with less power needed. Higher performance compared to standard spark plugs. Taper Cut ground electrode (Better flame spread). 2 to 3 times more lifetime in comparison with standard plugs. Better stability. Less fuel consumption. Stronger accelerations / More reaction from the engine. Corrosion proof alloy. Cleaner combustion / Less unburned fuel. Easier cold start. Smooth Idle / Less vibrations. Price is only for 1 spark plug. We advise customer to get 4