I've used a few good zappers before, but the Ultimate Zapper http://zap.intergate.ca/ seems to be the most powerful, it has a lower frequency and penetrates deeper. One thing is for sure: handholds are better than the wrist strap ones. It cured my insomnia to the point I cannot zap in bed or I will fall asleep, took away a wart and a cold sore in 48 hours, kills parasites and virus. For me using the handholds was the most powerful just holding them, others get better results placing them across their belly. I used that and Dr Hulda Clark 's Zapper to cure my Epstein Barr Virus (Chronic Fatigue Syndrome) I had Chronic-Fatigue-Syndrome for 11 years--yet with the zapper and parasite program was cured 80% in 60 days, the remaining 20% I used the Candida Wellness Program. Dr. Clark's zapper also made an infected skin tag on my neck completely disappear in a week. But to answer your question which zapper to use? Most all zappers will work and darn good too. But in my opinion, the Ultimate Zapper is the most aggressive one because it is a lower frequency. I have 13 cats who were worm infested with Ascaris and I had blurred vision and other symptoms which I assume was toxoplasma from the cats' feces and not washing my hands properly, so I wanted to get the most powerful parasiste program that worked the fastest, and listed below is what I feel is the best. I did for 30 days with great results:
HERE IS THE PET parasite PROGRAM FOR CATS (not humans with cloves or Wormwood ) and it's clear, odorless, and tasteless so the cats just drink in their water and don't taste or smell a thing.
PARALIXER(HOMEOPATHIC HERBS): http://www.ihealthtree.com/paralixer-2oz-king-bio-natural-medicines.html (CLEAR, ODORLESS, TASTELESS--USE 3-6 DROPS PER 2 CUPS OF WATER PUT RIGHT INTO PET'S BOWL (30 DAYS) THEN 1X PER WEEK FOR MAINTENANCE. No tricking or disappointment or wasting of products due to the cat smelling cloves or refusing Wormwood ! I'm using it now and NONE of my cats notice it at all, not even the picky ones.
Here's the ingredients: (The are all homeopathic/herbs - some of these herbs are their Latin names, I looked up each one up and Like "Tanacetum Vulgare" which is the same as the common herb names “Tansy, bitter button, cow bitter, golden button, mugwort.”
Calcarea Carbonica, Chenopodium Anthelminticum, Cina, Croton Tiglium, Filix Mas, Gambogia, Granatum, Lycopodium Clavatum, Mercurius Corrosivus, Natrum Phosphoricum, Santonium, Senna, Spigelia Anthelmia, Stannum Metallicum, Tanacetum Vulgare, Teucrium Marum, Zingiber Officinale - . Each ingredient is in equal volumes of 10x, 30x, and 100x potencies in a pure water base.
Most of them remove and kill parasites, but some help with the soothing of the stomach to assist in parasite elimination (some of the cats put on a parasite program will vomit the 1st day--due to the parasites dying) so the other herbs that assist in the mixture are very beneficial, which is another reason to use PARALIXER.
Of course, for humans, I only recommend THE ULTIMATE ZAPPER and the HUMAN PET PARASITE HERBS! People shouldn't share their bowls nor their zappers with pets anyway.
COLON CLEANSER IS A MUST AND SO IS DRINKING AT LEAST 2 PINTS OF WATER OR MORE PER DAY.