Used for threads which have been previously repaired and failed. BIG-SERT is a heavy wall solid bushing, easy to install with positive placement. BIG-SERT gives increased load protection for critical use. BIG-SERT will repair oversize holes which have previously been repaired. These kits will repair holes that were repaired by helicoil, perma-coil, uni-coil, recoil or any other similar coil style insert that has failed. NOTE: Bottom few internal threads are incomplete. he install driver seats the insert and completes the bottom internal threads locking the insert in place. This pushes the pin out to contact the threaded hole. Back out of the insert is prevented by the cam lock effect of the pin. Big-Sert Metric Kit M6X1.0 Provided Insert length is 9.4 metric. Thread Kit Contains: Drill, Counterbore, Tap, Installation Driver, (5) Steel Inserts.