I suffered pain in my shoulder for more than 6 months. One day I walked into a retail location in Las Vegas, that let me test this system. I tested it for 5 minutes at the store, and when I left I felt that it had reduced my pain in a significant manner. The pain returned later on but the experience left me curious about the possibilities of using this system. So I bought one here in Amazon and I used it at home several days, placing the electrodes in my shoulder. The unit is extremely simple to use and it works. Within few days my pain had subsided and never returned. It may be coincidence but I don't think so because nothing treated my pain effectively before for more than half a year. After 1 week using the system I recovered complete mobility and the pain was gone. Electrical stimulators (TENS) are used extensively by physical therapists and chiropractors. They appear to work by stimulating some sensory nerves that in some ways reset the painful nociceptors from the skin and muscle, in some people this can lead to lasting pain relief. This was my case, and therefore I recommend this unit because it worked, it is inexpensive and very simple to use.