Reflective material is also called retro-reflective material, the simplest retroreflector is a glass sphere or bead. When a light beam, such as headlight, is directed at it, the majority of the light will bounce off, but a significant amount passes through the front surface, and it bent or refracted towards the center of the rear surface. Some light hitting the rear surface of the glass beads is internally reflected back through the front surface of the bead and reflective onto a course parallel to the direction from where it came.
