4 Way Reflective Solar Markers. These studs, or road reflectors, are just like reflective road studs but use solar energy to power embedded LED lights. Additions of embedded LED light in each stud give these reflectors a significant advantage over traditional studs by increasing drivers reaction time. Since reaction time is mainly based on vision, solar road studs can give drivers up to a 30 second reaction time as opposed to a 3.2 reaction time from conventional road studs.