I'm not understanding the difference in the various machines talked about.  
There's the Dr. Beck's Pulser, the Dr. Clark's Zapper, and there's a Tens 
Machine.  One site (noted below) had several of these for sale, and indicated 
the different frequencies.  Can anyone explain if there is any real difference 
in final outcome or are these all pretty much the same. 

Thanks in advance,

Cindy
  

Frequencies of 4Hz, 16Hz and 100Hz selectable for use as Dr. Beck's Pulser with 
built-in digital timers.

Frequencies of 2128Hz, 10kHz and 30kHz selectable with a pre-programmed zapper 
sequence for use as Dr. Clark's Zapper.

http://www.myholistichealthshop.com/zapper.html
  Dr. Bob BECK, one of the CS developing Giants (recently deceased) declared 
that by using his Protocol (available from SOTA Instruments, 
Inc.--1-800-224-0242). Also, V at v...@powerlessons.net makes a marvelous 
Godzilla/BECK zapper/ziller