ODST armor
From Halopedia, the Halo wiki
The ODST combat armor or Body Suit, although similar to standard marine armor, and used by the SPARTAN-IIs before they got their MJOLNIR armor, is a specially designed suit. The suit itself is composed of a helmet, body armor and boots/gloves, and a back piece. They could deflect a small caliber round, one smaller than a 5mm bullet (used on Machine-guns/Automatic Rifles in real life). They have refrigeration and heating units that mask infrared signatures. The body armor and boots/gloves are fully encased and are air tight, making them capable of use in a vacuum. The integrated helmet has encryption and communications gear, a Heads-Up Display, and thermal and motion detectors. When sealed, the unit has a fifteen minute reserve of oxygen to let the wearer survive in vacuum.
Appearance
The helmet's appearance is much like that of the marine armor, but is fully encased and has a wide "v" shaped visor that is reflective blue. The helmet is flat black. Body suits are the matte black, form fitting, lightweight polymer body armor. The body armor has a black and gray camouflage pattern on the limbs, and flat black on the torso and boots. The armor has a total of six pouches on the waist, four smaller pouches on the chest, and two large holster-style pockets on each hip. The back piece is shaped like a small backpack, and contains a pressurized air tank that can supply the user with clean air for a total of 15 minutes. Below the back piece, there is a small solid sheath that can hold a combat knife.
Disadvantages
Unfortunately, the suits are uncomfortable over prolonged periods of time and tricky to repair in the field. Also, in desert, forest, jungle, and arctic fighting, the black color of the uniform is very visible. So it is probably suited for only night, urban, or space operations.