The blind spot of a vehicle is the area towards the rear that you cannot directly observe when you are at the controls and facing forward because they are not within the range of the mirrors.  Vehicles in adjacent lanes can fall into these blind spots. Therefore, when you want to change lanes or merge lanes, a collision can occur.
Blind spot mirrors are devices that fit to the wing mirrors of your vehicle to improve the rearward vision. They can be a variety of shapes, including circular, fan and rectangular. They are usually a convex mirror car gadget that magnifies the view from behind.