The C.S.S., short for Communication Safety System, is a
streamlined housing of high-intensity LED lights. This light
system warns oncoming trail traffic of the riders in your
group, eliminating the need to use the unsafe, outdated
hand signal system. The group leader and his/her followers
all display yellow, while the last rider displays green.
Yellow indicates caution, riders approaching while green
indicates the last rider of that group. This system also
has a hazard mode which is indicated by a flashing yellow.
The hazard mode alerts oncoming riders of trail hazards.
Simply put:
See yellow – traffic approaching
See green – end of that group or riding alone
See flashing yellow – trail hazard ahead