What is the function of the high-mounted stop lamp?

[DiBrayden]

The function of the high-mounted stop lamp is to alert vehicles behind to avoid rear-end collisions. For vehicles without a high-mounted stop lamp, especially low-chassis sedans and mini cars, the rear stop lamps are usually positioned low and not bright enough during braking. This makes it difficult for drivers of following vehicles, particularly those with higher chassis like trucks, buses, and coaches, to see clearly, thereby increasing the risk of rear-end collisions. The high-mounted stop lamp is generally installed at the upper part of the rear end. Since most vehicles already have two stop lamps installed at both ends of the rear (left and right), the high-mounted stop lamp is also referred to as the third stop lamp, high-mounted brake lamp, or third brake lamp.