With metal poles and ladders, these scale signals look great along your right-of-way. The 3-position semaphore has a realistic slow motion. The base has optical sensors built-in with a sensitivity adjustment. Just apply power and put them next to the track. The signals do the rest. When a train is detected next to the signal, a motor moves the blade to the stop position and displays RED. No power is on the motor in each position. Four (4) seconds after the train passes, the signal changes to caution showing YELLOW. After three (3) more seconds, the signal returns to clear showing GREEN. Signals have separate inputs and outputs so they can be daisy-chained: the down track signal will hold the up track signal on yellow until the down track signal goes off red.