Combine Lights are portable light sources used to illuminate dark areas in support of Combine operations. They are often mounted on walls or tripod bases, and can be found in many areas, from small outposts to inside the Citadel itself. Interestingly enough, the beam's direction is not directly tied to the direction the device itself is facing, suggesting that it employs some means of channeling its light in a certain direction internally.
These devices produce a bright, turquoise-colored light and appear to have an internal power source, as they are not visibly connected to any wiring. On the other hand, some lights on the rock face around the Citadel are connected to it by wiring, suggesting that they are simply recharged or connected to wiring in the walls or buried underground.