What is the greatest advantage to using a wireless clip-on microphone?

You can put your hands in your pockets so that you will not appear nervous.
You have the ability to hold papers in your hands so that you can read directly from the text when giving your speech.
You cannot whisper or shout for dramatic effect.
You can have both hands free in order to gesture during your speech.

The greatest advantage of using a wireless clip-on microphone is that you can have both hands free to gesture during your speech.