This is a mini Kreg pocket hole jig. I'm going to use this (for the first time) to assemble the
face frames that go on the bookcases. I didn't purchase the full ($100+) kit, just this mini.
This shows how it works: The drill bit and jig prepares a slant hole that receives a self-tapping
square hole screw that is centered on the two work pieces to be joined together. The clamp ensures
the two pieces are correctly aligned and flush. It's a pretty "idiot-proof" system that worked
straight out of the box. What is shown here is just a test.

But I think I've found a new toy. :)