There are areas of the road, behind the car and to the sides, which are crucial to be able to see, in order to drive safely, which are out of the driver's peripheral vision. The rear view mirror auto dim on a car is an electric interior mirror which allows the driver to see the 'blind spots' behind the car, enabling clear vision of any traffic nearby and any potential hazards, and as such is an important visual aid and safety feature.
The auto dim rear view mirror is housed in a casing, which contains an electronic circuit board and photo-sensors, and is mounted centrally, usually to the top of the front windshield and can be adjusted vertically, horizontally and diagonally to suit the height, line of sight and seat position of the driver.
The clever automatic dimming feature on this electric model reduces the glare in the rear view mirror from cars travelling behind. Intelligent photo sensors, which sense the amount of light hitting the rear view mirror, activate an electrical charge which is sent to the electro-chromatic glass, which automatically dims the mirror according to the light.
The rear view mirror glass should be clean and free from scratches, chips and cracks, to enable clear, safe vision. Rear view mirrors come in different shapes and sizes, dependent on the make and model of car, so it's important to ensure that you replace the rear view mirror with a part that is compatible with your vehicle.
Broken, smashed or chipped rear view mirrors will, of course, need replacing. Over a period of general use the auto dim rear view mirror will suffer from general wear and need replacing with an auto dim rear view mirror that is compatible with the make and model of your car.