Heh...from the title I thought he was talking about the music genre.
But to further clarify:
If it's a little one, then it's to adjust the height of the bridge saddles in order to set the action.

This shouldn't be messed with just to see what happens...prolly only an experienced tech should mess with that, thus I don't think you'll get much use out of it. Although I've found some cheap Wal-mart furniture is put together with one. :)