In fact, there are some differences between different wavelengths of light, mainly for symptoms. Near infrared (NIR) is the infrared with the shortest wavelength and the strongest penetrating power, which can penetrate human tissues by 5~ 10 mm, while far infrared is mostly absorbed by the surface skin, with a low penetration depth.
3a, far infrared is a kind of infrared, as mentioned above. The curative effect is related to wavelength, intensity and irradiation frequency. Philips is expensive because it has done a lot of research and development work before production, not only the research and development of the equipment itself, but also the research on the mechanism of action. The mechanism mentioned here is not the broad description mentioned above, but the influence of different wavelengths and intensities of light on cells. Which ion channels on the cell membrane are affected? How does it affect neurotransmitters and hormones? How does the change of ion channel affect the cell activity? These investments are very large (plus universities and laboratories), and the quality of Philips equipment is definitely better. But many domestic manufacturers have not done these studies, so there is such a big difference in prices, and you can also judge the quality and efficacy by yourself.