Items such as lamps or torches. TL1-3 versions burn (via oxidization of a fuel such as wax or oil) and therefore require an atmosphere, and may have reduced duration. TL7+ versions may either be chemical torches, which operate without electrical current, or high-efficiency lighting elements. Typical lamps spread light across a wide angle, and may have shields to direct the beam.
“Traveller 5.10 Core Rules Book 3 : Worlds and Adventures”, Miller, Marc , Far Future Enterprises