Many cars - generally on the 6 - feature LED lights on the sides of the cars around the rollsign where the service logo is indicated to help riders distinguish between an express train (red diamond) and a local train (green circle). These indicators were first introduced on the when passengers claimed they could not clearly hear the announcements regarding whether the 7 was express or local, even though the 7 Express sign was used on the front and sides prior to its implementation in 2008. Cars 1736–1740 and 2151 were used as test cars as early as April 12, 2007, and had red LED lettering displaying "LCL" and "EXP" on the front and the side; similar labeling was last seen on the Redbird fleet. When the R188s displaced the R62As from the 7 during the 2010s, the LED lights remained in use since both the 6 and the 7 local services have express variants that run in the peak direction during rush hours.