Going back to 1973 when Meyer first introduced plow lights, the originals were just round headlights. There were no turn signals on them. The first plow lights used that had turn signals were the Signal Stat lights. They had a A/B selector switch in the cab that allowed you to choose between the plow lights or vehicle headlamps. They were spliced into the vehicle headlamp wiring, and routed through the A/B switch in the cab. Signal-Stat was purchased by Truck-Lite.