Video describing the difference between a digital tens unit and an analog tens unit for pain relief. How to use a tns unit, tens unit. Video shows a digital tns unit beside an analog tens unit explaining the width control, tens rate control, amplitude (power) control and how digital tens and analog tns devices differ using buttons, not knobs. Digital tens units have screens whereas analog tens units use buttons for the patient to adjust the tens power for pain relief. Tens units are used to treat RSD pain, treat fibromyalgia pain, treat sciatica, treat low back pain, treat arthritis pain, treat foot pain, treat shoulder pain and treat chronic pain without use of drugs.