200 Pcs Helicoil Thread Repair Kit, M3-M8 Metric Thread Adapters, Reducing Nut

Practical Design: The helicoil thread repair insert kit is mainly used to eliminate the deviation between the threaded hole and the tooth plate, which can firmly lock the screw in the threaded hole, enhance the thread connection performance, and ensure that the screw is not easy to loosen during vibration.

eBay