This was an offer I sent to someone who said they could bring 300 people. So if they weren’t exaggerating, they would get the full guarantee, but this way I also protected myself if they were misrepresenting themselves.
You isolate the harmonics on a guitar string by lightly touching it in certain places to deaden some of the vibrations. If you touch the vibrating string at its halfway point, you can hear it vibrating in halves. (On the guitar, the halfway point is right at the twelfth fret.) If you touch the string a third of the way along its length, you can hear it vibrating in thirds. (On the guitar, this point is right at the seventh fret.) Each whole-numbered fraction of the string produces a different harmonic. The shorter string sections produce higher and quieter harmonics.