Great
The last time I used TENS units was when I was playing football in college.  Fast forward quite a while and now I have this unit.  I love it.  There are already some detailed reviews up but let me add this:  even though I had never operated one of these on my own, I was able to figure it out thanks to the directions and the presets on the device.  Thus, if you have never used a TENS unit, I can recommend this one to you because of it's ease of use.
Rating: 5 stars