The story and theory and technology of Royal Raymond Rife is indeed intriguing and probably true since the experiments and results were apparently reproduced by others people.
But this is not because a technology/device existed and was efficient in the past that the devices sold by zappers/frequencygenerators sellers nowadays are the same or are efficient.
Just take a look at the CAFL and realize the nonsense it is, they confuse diseases with infectious organisms... (do you really think you will manage to cure instantly mercury/lead poisoning or physical trauma/wound or nutrients defficiencies with an electric wave or an electromagnetic wave ? seriously...)
Also after all these sales, can any of these zappers/frequencygenerators sellers show one objective proof that what they claim is true ? (an experiment done at home is ok) If no what is the excuse ?