Zero is hard to leave alone once it's in your hand. It's something about the clicks and haptic feel of the retract. On extension, the internal mechanism makes a really satisfying click due to the beefy key snapping into the locked position.

We devoted many hours and several iterations to create a design that does not use screws and does not require a tool to disassemble. Some of the internal mechanism is similar to the tricks used inside a mechanical puzzle. 

Zero is capable of accepting various blade types from most major manufacturers.