TENS: "Transcutaneous Electrical Nerve Stimulation"- a non-invasive, drug free method of pain relief used by Physical Therapists and professional Doctors for over decades. By delivering stable pulses to the skin to stimulate nerve fibers, Tens unit could effectively block the pain signal to people’s brain. At the same times, increases natural endorphins, which is a natural pain reliever. In many cases, the reduction or elimination of pain lasts longer than the actual period of stimulation