Not to be used as a tap.
Performance Tool W80539 Spark Plug Hole Thread Chaser - 18mm
Performance Tool Spark Plug Hole Thread Chaser - 18mm W80539
Spark Plug Hole Thread Chaser 14mm and 18mm Cylinder Head Re-threader Tap tool
2PCS Spark Plug Hole Thread Chaser 10 12 & 14 18mm Re-threader Tap Cleaning Tool