Powerbuilt 640811 Back-Tap Thread Repair to Back-Tap's patented collapsible design allows it to engage be placed through the spark plug hole and into the chamber The Back tap repairs the damaged thread as it is drawn up through the spark plug hole Made in USA. Meets or exceeds ANSI standards. Back-Tap 14 millimeter thread straightening tool for spark plug fouled threads Collapsible design allows it to engage be placed through the spark plug hole and into the chamber Expands the tool's threaded area and threading into the clean threads Backtap repairs the damaged threads as it is drawn up through the spark plug hole