End-of-Roadway Markers also called the Type 4 Object Markers, have their own category in the MUTCD. This type of sign may be designed in a button copy style with nine 3 ¼ inch red reflective buttons on a diamond shape aluminum panel. The panel shall have a red reflective or black non-reflective background (OM4-3). The most popular End-of-Roadway marker is a plain red retroreflective 18-inch diamond panel.