This kit includes 2 signaworks 4 diameter stop-go dock lights a 12 x18 depart on green only aluminum sign and a 9 x12 enter on green only vinyl sign. By default the product comes with a switch on the inside light that controls both lights alternating signals. When a truck is parked securely in the loading dock the inside light is turned green. This indicates to the forklift driver that it is safe to enter the trailer. When the green light is on inside the building the outside light is red indicating that the truck should not move. Once the truck is unloaded the inside light is turned to red. This tells the forklift driver to stay away from the truck. Simultaneously the outside light is turned green indicating it is now safe for the truck to pull away. The lights work in tandem with both signs to further communicate entry and exit with the lights. Brand: Signaworks Size: []