Denso (4709) IW20TT Iridium TT Spark Plug, (Pack of 1) Denso # 4709 0.4mm Iridium Center Electrode 0.7mm Platinum Ground Electrode Larger spark translates to more power and superior fuel economy 0.4 mm iridium center electrode: world's smallest diameter that maximizes firing potential 0.7 mm needle tip ground electrode: promotes higher spark energy and less 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