The Zero Tolerance 640 is a cool EDC pocket knife, designed by Ernest Emerson. This American knife maker is a pioneer in the pocket knife world. This Zero Tolerence 640 is a very interesting design. Undeniably Emerson, but different from his usual designs.
The 640 has a handle that fits well into any type of hand. This is because Emerson added a slight curve to the handle. There are also no compelling finger grooves to make sure the various grip options are almost endless. In terms of construction Emerson chose thick titanium liners which are flanked by a carbon fibre handle. This carbon fibre is very remarkable: it has a green glow. Zero Tolerance is one of the first large knife companies that experiments with that type of coloured carbon fibre.
You can open the knife with the thumb disc placed on the spine of the blade. This disc has a rich texture all around. As such you can easily and quickly open it with your thumb. You might expect almost all Zero Tolerance knives to be enhanced with ball bearings, the 640, however, has been enhanced with large phosphor bronze washers. Nice and solid and easy to maintain. In terms of steel ZT chose CPM 20CV. An incredibly stainless type of steel which retains its sharpness for a very long time. When opened a solid linerlock will block the blade. Because of the thickness of the liners you could almost talk about a framelock. The titanium lockbar has, of course, been enhanced with a steel insert to prevent wear and tear in the long run.