jumia"No one understands what harmonic resonance is. Maybe this would be a good starting point for anybody selling this product. Absolutely horrifying."
Please explain why you are horrified I hope you are not too frightened I am sure some here will be able to help you please reach out.
A clear explanation is found here:
ADD-Powr is making a claim or an assertion partially based upon this and the Fourier harmonic series:
They also have a useful animation video that attempts to explain their idea.