Red Light Device - Targets Injury Directly and Provides Joint and Muscle Pain Relief. Red Light lamp has Numerous Effects on the Body. RNear infrared light is best for deep tissues such as joints, muscles. Infrared light heats us and can help with detoxification. When infrared heat hits the targeted area, the warmth opens up the capillaries, improves the circulation, which It's effective for temporary relief of mior muscle and joint pain. RFAQ 1- How many bulbs does this product have What's the wavelengths Three in total, they are 630nm, 660nm, and 850nm. R2- Why only 2 bulbs are on Ris one of them broken Because 850nm is actually outside of the visual spectrum, it's invisible to human naked eyes. Actually it works, don't worry.