If you carefully observe the details of your life, then you will find that there are often magnets on car license plates that can be seen everywhere on the street. Its presence here is usually to make the camera focus. The small button-sized magnets on the car brand are mainly made of titanium oxide, rare earth metals, rare earth metal organic complexes, etc. The small dots are good infrared emitters, which can absorb the heat conversion of the car body or the surrounding environment. It is radiated by infrared rays.