The TNR Shoulder Lamp is a standard piece of equipment issued to combat personnel in the United States Colonial Marine Corps. A heavy duty mag-powered torch, it is typically attached to the harness of the Marines' M10 Pattern Ballistic Armor. There is a heavy duty battery pack just below the lamp's neck. Given the size and power source of the battery, one can guess that the shoulder lamp can stay on for a number of hours.
Newer models have a remote neck, which is connected to the marines helmet and moves the light in the direction the marine is looking in.