This is a very good version of this effect, however, I have learned a couple of others which are
cleaner. The gimmick is very well made, but it is a little suspicious in my opinion. He claims that
he's never been asked to inspect the final revelation card—but that indicates good audience
management skills, which are very important; and you do learn a little about that in the
instructions.
With some imagination, the gimmick can be used for a few other effects as well.