Emergency beacon

An emergency beacon

Emergency beacons were large hand-held lamps that could be used to illuminate dark surroundings, similar to palm beacons and SIMs beacons.

The beacon could be modified to emit only certain wavelengths of light. In 2367, Data modified a emergency beacon to work on ultraviolet light. In order to do so, he had to replace the regular emitter module. (TNG: "Identity Crisis")