REFLECTOR RED ROUND 3-1/4" W/ ALUM GROMMET. The RT-90 is the most popular model of centermount reflector and can be used on any type of sign or in any application. These centermount reflectors are made in the USA and meet or exceed Federal and State delineator photometric standards. In addition, it offers a bright, smooth exterior that helps to eliminate the build up of dirt and moisture.