
Each time you use a coil you usually drill a slightly larger hole (5/16 drilled with 11/32) than the actual size on the bit could thread be cut easily. All of these bits are the same size. Good for alum (slow), but you'll definitely break them on steel.

Heli-Coil 5334-14 Thread Repair Kit
11 Review

Thread Kits 1221-309 Thread ๐ง Repair Kit: Fix Stripped Threads with Ease
11 Review

๐ก Helicoil 5521-5 5/16-18 Inch Coarse Thread Repair Kit: The Ultimate Solution for Thread Repair
10 Review

๐ง Restore Threads with AB Tools M12 x 1.5mm Thread Repair Kit/Helicoil - 15pc Set (AN046)
11 Review