Communication and Controls Establish a clear line of communication between drivers and dock personnel. 12 1/8″ high x 6 3/16″ wide x 2” deep (light cover projects 3 5/8-“). Clearly visible green and red lights. Black polypropylene housing. Two 12-volt automotive bulbs. Inside toggle switch manually changes lights between green and red. Middle switch position provides “red-red” safety condition. One inside and two outside caution signs. UL Listed. Optional LED Package Extended bulb life. Lower maintenance cost. Cooler burning light system. Less AMP draw.