A TENS Unit is one of several kinds of electrotherapy devices that use very small doses of electric current to promote natural pain relief. A TENS unit is simple and easy to use and compact provide quick and dependable pain relief at work, home or play. Transcutaneous Electrical Nerve Stimulation (TENS Units) is a highly effective treatment for chronic and acute pain. It is used extensively and recommended by sports coaches, physiotherapy, pain clinics, doctors and other medical practitioners. A TENS unit will relieve pain, you should notice immediate results, and you can leave on for hours a day and for many the relief is dramatic.