Security uniform

The Security Uniform and matching Security Helmet are pieces of armor in Fallout 3. It comes in two versions with different visual appearances but identical stats.

Gameplay
Security uniforms and helmets are worn by guards in Tenpenny Tower and Rivet City. They are variations of combat armor and combat helmets.

Tenpenny Security Uniform
Khaki-colored security uniform worn by the security guards at Tenpenny Tower.

Rivet City Security Uniform
Black-colored security uniform worn by the guards in Rivet City.

Tenpenny Security Helmet
Unused green combat helmet that only exists in the game files.

Rivet City Security Helmet
A Black security helmet, similar in appearance to the Vault 101 Helmet, worn by the guards in Rivet City

Bugs

 * When worn by a female character, the Tenpenny security uniform has the green sleeves from standard combat armor. Bethesda used the standard combat armor mesh with an alternate texture, however, the 3D index for Arms02 was mistakenly set to 4 instead of 2 causing the texture error.
 * The above bug isn't an issue for the Fallout 3: GOTY edition. A female character wears the Tenpenny security armor without the texture clash. The color is exactly as seen in-game.