I have the BioStim m7 portable tens unit. It is very easy to use and I love it because I can wear it while I go about my daily activities. I just run the wires under my pants (for my ankle). It has an easy to read screen, buttons that are easy to understand and use, all the setting that are important, and it has held up to over a year of constant use. I use a constant setting as opposed to a variable/pulsing one and just amp it up as I need to for the pain. I will usually have it on for an hour and then once the pain starts to go back up I will turn it on again for another hour.

I bought a large number or replacement electrodes from amazon.com for a really great price. I would also recommend checking for the unit itself on there because they have some pretty good prices. I got an ultrasound heat therapy unit from there and it works great and was much cheaper than other places.