Böllhoff HELICOIL® plus repair wraps Threaded inserts for metals, steel. ISO metric screw threads. Content: Threaded Inserts, Twist Drills, Hand Taps HSS, installation mandrel, tang break. Dimension: M6 per 20 inserts in lengths of 1, 1.5, 2 d HELICOIL® plus thread inserts are made of austenitic chromium-nickel-steel (tensile strength of min. 1400 N / mm2) manufactured. The rolled nut thread has a high surface quality. This ensures a high-strength, wear-resistant thread with an extremely low constant thread friction and. In repeated screwing a higher and consistent biasing force is thus achieved with the same torque. This leads simultaneously to a better utilization of the yield strength of high-strength bolts. Significantly reduces the torsional stress is: Compared to cut threads, the surface roughness is low HELICOIL® plus up to 90 percent.