Light Force Therapy uses light-emitting diodes, or LEDs, to produce safe, low-level infrared light, which helps temporarily elevate muscle tissue temperature and increase local blood circulation helping to relieve pain and relax muscles. This FDA-approved device is completely safe and drug free and has no known side effects. Six settings plus a full cycle setting rotates through all frequencies. Includes instruction booklet, DVD and power adapter. Weighs 1.5 lbs. Covers 20 square inches.