Yes, that's exactly the problem. The pharmaceutical cartel's done everything they could to keep knowledge of them from being shared. Dr. Clark talks about them in her book 'cure for all diseases'. They send an electrical current though your body which kills parasites.
Many here are anti-zapper because they've used them wrong, or are trying to kill parasites which are really toxicity symptoms, or are probably too dehydrated, so it didn't work as well, or of course there are cartel employees who're being paid to misdirect, misinform and outright lie to keep people from even trying them because the cartel will lose gobs of money if people all kill off their parasites and become well. At least that's what I've figured out.
Zappers in general are basically frequency generators used to target various pathogens--electrocuting them with their own frequency (which are far lower than our frequencies and don't harm us at all). Clark's zapper works because of the square off set wave from the battery. You can download her book here for free, and chat with parazapper who is quite knowledgeable about them.
I believe Dr. Clark was holding back on what cancer actually was, since she cured it all the time in her clinic. She had to know what it was to zap it. I think she was being threatened by the cartel's flunkies in various government agencies so she made a deal. After all, 'cancer' is the cartel's biggest money maker--couldn't have her exposing that.