Flashlight

"UAC Standard issue light source. This model utilizes a static transfer power supply, so battery replacement is unnecessary."

- PDA Description

The flashlight is a tool and weapon in Doom 3. Its default key is F (White for Xbox). Its main purpose is to light up dark corridors, although it can be used as a weapon at close range. 

Ideal uses
The flashlight in lower levels can be used to attack zombies to conserve ammo. It has a slightly shorter range than the fists when used in this way, but is about twice as powerful. Attacking an enemy stronger than an Imp is not recommended. On higher levels, the flashlight should be used to light up dark corridors only. Upon sight of an enemy, a more powerful weapon should be swapped out. The flashlight could also be used to attack corpses on the ground to check that it is dead so that it does not rise again as a zombie. In deathmatch, using the flashlight alerts other people to your whereabouts. The weapon is not included in the Xbox version's deathmatches.

Trivia

 * The Doomguy's inability to attach his flashlight to a weapon in the game is often a subject of parody. Also, he should be using the Harries technique when wielding the pistol.
 * The flashlight seems to be running with batteries that have infinite life.
 * It seems to be unusually durable as it can kill zombies in two hits and still function.
 * In the BFG Edition, the flashlight has been replaced with a "mounted flashlight" on the Marine's armor, however the world model for the red flashlight still exists, although the player can't take it. The new mounted flashlight only has a limited time period (roughly 30 seconds) to use before it has to recharge itself again.