660 nm Buyers Guide
Body Area Covered
First, the body area covered is given 6" from the light source. Also, note that some of these devices are panels while others are bulbs.
Second, in some cases the light source is a panel of LEDs. While, in other cases, the light source is a bulb or lamp with LEDs. By the way, a panel emits light from a wider area than a lamp. So, it covers more of your body with uniform light energy.
Third, luminance or irradiance is the light energy emitted by the device. Incidentally, this energy is expressed as milliwatts per square centimeter. Furthermore, the further away you are from the light source, the less energy you will receive. So, for purposes of comparison, luminance values are given 6 inches from the light source.
Fourth, the choice of a device depends on the nature of the problem you are trying to solve. For example, if you are trying to treat skin in limited areas of your body such as your face or neck, a lamp would be a good choice. On the other hand, if you are trying to treat skin in large areas of your body such as your back or legs, a panel works best.
Finally, it's important to ensure you are comfortable with the guarantee or warranty that may or may not be offered.