Denso (5352 IK20G Iridium Power Spark Plug, 1 Pack 0.4 mm iridium center electrode: world's smallest diameter that maximizes firing potential U-groove and taper cut ground electrode: provides faster spark flame growth and lessens heat quenching DENSO patented 360 degree laser welding process: ensuring exceptional quality bond and structural strength with the iridium center electrode DENSO patented 360 degree laser welding process: ensuring exceptional quality bond and structural strength with the iridium center electrode Iridium Spark Plug Iridium Center Electrode Provides superior ignition performance during acceleration