I had an old TENS unit that my father was using back in the late 70s/early 80s. I tried it to see if it would help with the current state of my back pain, and it did. Since it was a very old design it was a single mode with only control over the intensity of the 2 channels, but since it did work I wanted to get a more updated unit.Not only does this unit have many different modes, it also has WAY more intensity within its range. Operating this unit is really very easy and intuitive, however figuring out the best placement options for the pads along with which mode and intensity settings to use is a bit of a learning curve (trial & error). At the moment it seems that the lowest intensity settings are best for the pain I'm dealing with. Higher intensity settings may not feel uncomfortable while the unit on and doing its thing, but those higher intensity settings tend to over stimulate the area and make the pain worse. Just remember to go slow and make VERY small adjustments and this unit will have MUCH greater potential for good results.I also like the way the wires attach to the pads much more on this unit. My old device from the 70s or 80s connected to the pads with a slide in connection that plugged into a little pigtail wire that attached to the pads. This was problematic because when you sit with you back leaning against the seat back of the chair it would tend to pull on the pigtail connection and expose the wire. This unit's wiring attaches to the pads with snaps and it is far less likely that this type of bare wire exposure can happen.So there you have it, and great product with a bit of a learning curve that will serve you well for years to come.