A spotter mirror is a small, additional mirror that is mounted on the side mirror of a vehicle. The purpose of a spotter mirror is to provide a wider viewing angle for the driver, particularly in the blind spot area, which is the area that is not visible in the main side mirror.
Spotter mirrors are particularly useful when changing lanes or merging into traffic, as they allow the driver to see vehicles or objects that may be hidden in the blind spot. They can also help improve overall visibility, making it easier to navigate in tight spaces or maneuver around obstacles.
The use of spotter mirrors can help drivers to increase their awareness of their surroundings and avoid accidents caused by blind spots.