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there is one thing that I do not understand and that is why would someone go and spend $150 to $250 for a single frequency zapper when they can get 14 different frequencies in 6 different modes for only $109 US plus S&H ?
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because your argument that using several specific frequencies (chosen how ?) instead of one is arbitrary and there is no proof that it is more effective to kill some harmful organisms.
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The answer is that people buy a lot of hype.
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and that's why some people will keep buying your devices... There is a never ending stream of ignorant stupid gullible people with money to throw away at you if you can provide an alternative treatment which sounds/looks hightech/magical (even if it is totally ineffective) (i was one of them in the past)