Warning: This is not repeatable...for the same audience or for anyone witnessing the performance. This weakens the effect to the extent that it is completely worthless. With this type of effect it is necessary to perform it more than once for it to have any "credibility". For what it is, it is way over priced for what, to me, is essentially a trick based more on semantics and is no more than a gag. Like all of us, I've bought a lot of useless, worthless crap but this is the first time I'm writing to give anyone a heads up. My suggestion is to spend your hard-earned money (or however you've earned it) on something more worthwhile--maybe some X-ray glasses or a gizmo which allows you to throw your voice.