There are twice as many explanations as to how a frequency instrument works as there are frequency instruments. Most of these explanations are wrong or woefully incomplete.
In principal however, any effect that is powerful enough to kill a tiny microbe, but does no harm to the body is bound to work to some degree. It’s unavoidable.
The average user is totally results oriented, doesn’t really care if the theory we hold is correct or not, so long as it works reliably.
Manufacturers can be results oriented as well, applying the best theories according to what has worked well in the past.
A master of frequency therapy can determine almost exactly what a machine can do, based entirely on its output. He can usually get results with any device that has the right output.
Even with the ideal equipment and support, the challenge is always to make the therapy work for that person or situation.
Given a mastery of the therapy and equipped with the most optimum device, it is no longer a question of the machine, or how it works. The machine cannot fail to do the job it was designed for. It becomes a question of how well we use that tool, and how well we work.