I had an apple slicer on my desk at work and one of my co-workers asked, "Why do you have an apple slicer on your desk?"  This is what's known as a "dumb question," because an apple slicer performs one function, and one function alone:  Slicing whole apples (technically it cores them as well, but it's essentially the same thing).  An apple slicer is a great example of what can be called a "unitool" which, as opposed to a multitool (one tool that performs many functions) or a polytool (one tool made up of many tools that all perform the same function), does one thing and does it well.  Another co-worker walked by my desk and commented how a unitool (or "unitasker" as he called it) is pretty uncommon because of the abundance of multitools, and also unnecessary in that the same function can be achieved with a simpler tool like a knife.  While these are valid arguments, I think it's worth the trouble of carting around a tool that's only good for one thing, simply because it performs that function in the best possible way.  Function over form. #products