UNSC Navy working uniform
From Halopedia, the Halo wiki

Working uniforms are part of a uniform (much like fatigues) worn by military personnel in non-combat situations, such as the crew-members aboard the UNSC Pillar of Autumn[1] and UNSC In Amber Clad.[2] They provide little to no protection, only offering a covering specifically for their jobs and tasks at hand, such as bridge crews, engineering and tech support on ships or ground-side.
Gray service coveralls are the basic uniform worn by UNSC Naval personnel while on duty.[3][4] These uniforms offer only a little protection. For specialized personnel, they come in a variety of colors such as blue, red, orange, purple, and yellow. The colors often differ depending on the wearer's job.
Trivia
The color-coded working uniforms seen in Halo: Combat Evolved and Halo 3 are almost identical to those worn by BOBs in the Marathon trilogy. However, in Halo: Combat Evolved Anniversary, all Navy personnel aboard the UNSC Pillar of Autumn wear gray two-piece uniforms which resemble those seen in Halo Wars, Halo: Reach, Halo Legends, and other more recent media.
Gallery
The Naval uniforms seen aboard the UNSC Pillar of Autumn.
List of appearances
- Halo: Combat Evolved (First appearance)
- Halo: The Flood
- Halo: First Strike
- Halo 2
- Halo: Contact Harvest
- Halo 3
Sources
- ^ Halo: Combat Evolved campaign level The Pillar of Autumn
- ^ Halo 2 campaign level Delta Halo
- ^ Halo: Contact Harvest, page 322
- ^ Halo 2 campaign level Delta Halo