The marker light consists of a battery and lightbulb in a metal or plastic shell. There is a switch to turn the light on or off. The batteries last for about six hours. An marker produces a sphere of light about 5 meters across in all directions.
A marker light can be seen by others in line-of-sight from many kilometres. The light may be coloured, caused to flash in various patterns and from TL–6 and over, may emit in wavelengths other than visible light (i.e. Various wavelengths of Infra-Red or Ultra-Violet).
The duration of the light will extend with higher technology levels, for equivalent illumination and for the same cost.
These lights have military applications for confirming target zones for fire, landing zones for troop or equipment drops, etc. when other means are not available for technological or other infrastructural reasons.
Marker lights may be thrown, and versions exist that are fired from grenade launchers.