The 3x cornered mirror has 3x front surfaced mirrors mounted inside a plastic moulded housing such that the 3x faces are mutually at 90 degrees. A special mirror of this type always reflects the incident ray back to the source regardless of the angle of incidence. Miniature mirrors of this type are in reflectors used on the road and on posts beside the road. They always reflect back towards the vehicle's headlights even if illuminated from an angle.