Powerbuilt 641148 12mm Back Tap Thread Repair Tool 12 Back-taper 12 millimeter thread straightening tool for motorcycle 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 Built to exceed tool standards Highly durable Back-Tap 12 millimeter thread straightening tool for motorcycle 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