The CHMSL generally installed in the rear of the upper part, so that vehicles traveling behind easy to find the vehicle in front brakes, played for the purpose to prevent rear-end accidents. General Automotive has two brake lights installed at the rear ends, either side, high brake lights, also known as the third brake light.
The CHMSL role is to alert traveling behind the vehicle, so as to avoid rear-end accident. CHMSL vehicles, especially the lower chassis cars and mini car braking due to the lower position of the rear brake lights, usually brightness is not enough, followed by driving vehicles, especially the higher chassis trucks, buses and public the driver of the car is sometimes difficult to see. Therefore, the hidden danger of a rear-end accident.
A large number of research findings that high brake lights can effectively prevent and reduce the incidence of rear-end accident. Therefore, CHMSL has been widely used in many developed countries. For example, in the United States, from 1986 in accordance with the regulatory requirements for all new cars sold must be equipped with high mounted stop lamp; CHMSL must be installed from the beginning of 1994 all sales of light trucks.