Proved and tested for over 65 years: HELICOIL® thread inserts create highly resilient joints in metal materials with low shear strength. Every thread of the thread insert with precision-formed, rhombic profile is free running. The result is an internal thread true to gauge that can be used from both ends. The HELICOIL® Plus Free Running is coloured green to allow for easier identification when it is installed. A diamond-shaped imprint on the end of the last turn on every HELICOIL® Plus Free Running marks it as an unmistakeable original by Böllhoff.