It is mostly used in an underground environment, like mines or during outdoor activities, e.g. climbing.
A patent for a self-adjusting bracket for use with cap lamps was awarded in 1985.
The GEN 4 model, approved for use by the Mine Safety and Health Administration (MHSA), uses the headpiece of existing cap lamps, but retrofitted with new LEDs and electronics.
These lamps will last up to 50 hours with a six-cell battery pack.
[2] These new cap lamp variants that use LEDs follows research done by the National Institute for Occupational Safety and Health in the United States, comparing LEDs to traditional incandescent light bulbs, where they found that the LEDs improved hazard detection.