I am gonna install a passenger mirror, so I drill the two holes, buy this tool, insert the rivets and screw in the screws? Do I need special screws?
Basically yep! It's like a pop rivit that has threads inside. The tool threads into the insert, put it in the hole squeeze and it swells the part you just put in the hole and pulls tight to the sheet metal so it won't spin.
I can't remember exactly why I didn't use the suplied screws...it was either they were the wrong thread for the inserts that come with the tool ( 10-24 or 10-32) or it was because they were not stainless and I wanted stainless.
I did have to slightly turn down the heads of the screws , so they fit in the mirror holes. You could do the same with a disc grinder and spin the screws to make the head smaller...You can't see the outside of the heads of the screws when it's installed.