Just put it on and the pain is gone. The Evertone Forever Back Plus Pain Relief System uses Transcutaneous Electrical Nerve Simulation (T.E.N.S.) technology to alleviate pain associated with sore and aching muscles in the lower back due to strain from exercise and normal household or work activities. The featured T.E.N.S. system stimulates the body’s natural pain killers for effective pain relief and is doctor recommended. The Forever Back Plus system also provides much needed lumbar support. The adjustable belt system fits waist sizes 26" to 50". Includes 1 dual channel digital stimulator module, 1 Forever Back Plus support belt, 4 adhesive pads, 2 snap cables, 1 9v battery, user manual and warranty card. WARNING: Do not use this device if you have a cardiac pacemaker, implanted defibrillator, or any other implanted metallic or electrical device. Pregnant women should consult their physician before using this device.