I wonder how long the battery lasts?
more info on Smart TENS - http://www.smartrelief.com/faqs/

If someone is sitting most of the time, a TENS or IF stim with a AC adapter (plug in) will work nicely and not use so many batteries.

I think these kind of things are great, no side effects..
I have had my IF stim since 2011- ( $90.00 on Amazon back then)