The GTI lock stands for GUTHRIE TUNGSTEN INSERT. It features a Tungsten Carbide Insert fitted into the lock face of the R.I.L (Reeve Integral Lock) Tungsten Carbide is incredibly hard, achieving 90HRC on the Rockwell scale. This high hardness reduces lock wear greatly. A knife fitted with the GTI lock is guaranteed against any lock wear that will induce lock rock or vertical blade play.
This term refers to the maturing of the lock as wear takes place. The very small amount of lock wear (which now moves to the hardened blade) that could occur with the GTI lock has proved to be beneficial. It does not have the same detrimental effects as the lock bar wearing. Slope force is the sideways force the lock experiences when the blade is pressed against the lock. Increasing the incline on the blade lock face, increases Slope force. Increasing Slope force decreases reliability as the greater force wants to push out the lock bar, resulting in lock failure or lock slip. When a lock bar wears, it wears to the same incline it is being pressed against. In this case the incline of the blade. Slope force now increases and reliability decreases. With the GTI lock, the opposite effect happens. The Tungsten Carbide wears the blade to a shallower incline, which decreases Slope force, resulting in more reliability as time goes by.
Due to the nature of this exceptionally hard lock, it is not guaranteed against any spine whacking. Used as a normal cutting tool, this knife should never run out of lock life.