Emerson Wave - Opening Systems
Emerson Wave Info
Ernest Emerson patented the wave in 1999 and ever since then, the wave has been a popular feature on production and custom knives of the tactical variety. The wave is a small protrusion on the top of the spine near the thumb stud of a knife that catches on the corner of your pant pocket when you are pulling the knife out, causing the blade to open simultaneously as you are drawing the knife. The wave is commonly considered the fastest way to open a folding knife.
Spyderco has a production version of their own wave as well, though not quite as pretty, they are functionally identical. They can be found on the Endura and Delica Wave folders.