12-volt Maltese iron cross brake/tail lamp (with license plate light) and chrome die-cast housing.  The two-wire hook-up means the light is self-grounding.  The red wire is a 12v positive brake light.  The black wire is 1a 2v positive running light.  The light uses a standard incandescent automotive 1157 bulb(included) with dimensions 4.25" wide 3.875" tall, 1.875"thick, and 2" bolt-hole spacing.