I have heard good things about them, the one time I used it I felt it was working, had some die off symptoms. I do not really know that much about them. I researched it before I bought it, I was so sick at the time I thought it would help. I am symptom free, and really would like to use it for maintainance, but I just never have the time to use it. Anyway, there is alot of evidence out there for the zapper's etc. helping with parasite elimination and alot of people that use them on this site-(primarily why I bought it) Like I said I just never found the time with my schedule. :) Cindy.