In the beginning, there were rocks. Then man began to forge fixed-blade knives. Then comes the friction-folder, and from that point forward there have been scores of mechanisms used to open a folding knife. The site 25Ideas.com compiled a list of the 15 most unique, like the Kershaw ET:
The Kershaw ET uses a toggle mechanism to open and close the blade. You can actually engage the blade through many ways (using your thumb like a traditional folder and dropping the handle while holding the blade), but the toggle is probably the most fun. You can use a lever near the butt of the handle to open and close it. The knife was discontinued, probably because there’s the danger of the knife closing on your thumb when you use the toggle.
I don’t want to steal their thunder, check it out for yourself. Each knife has its own animated .GIF, and it shows a wonderful variety of somewhat out-there knife opening mechanisms. Here is my favorite:
The Lone Wolf Defender was the 2009 winner of the Overall Knife of the Year award at Blade Show. The designer of the knife, Paul Poehlmann, invented the Paul Axiel locking mechanism, which can be seen on the Defender and a few others.
One way to open this knife is to hold the pivot between your thumb and index finger with the handle pointing upward. When the pivot is depressed with your fingers, the blade unlocks and the weight of the handle will cause it to fall, revealing the blade. To close it, you do the same thing but in reverse.
Which one is your favorite?