It's this piece that when you press on it it pops out (not the CD tray if that's what you're thinking, I'm not that slow). It's a flat piece of plastic with some rounded rectangles cut out of it, and the company name on it and two prongs on the part that goes into the computer. Above where it pops out it has an icon in the shape of a card with the letters EX on it.
I call it the tazer. lol. My comp has a remote that goes in there.