Unggoy combat harness

The Unggoy Combat Harness is a type of body armor issued to the Covenant's Grunt warriors. It provides basic protection from hostile fire and the elements, and is also equipped with a breathing apparatus for the methane breathing aliens.

Breathing Apparatus
The gas is stored in cooled tanks inside the suit, and is provided to the user through a breathing mask that covers over half of the alien's head. The methane is supercooled for storage. The triangular backpack attached to a Grunt's back contains a small methane tank. Attached to every Grunt's wrist is a readout (measured in Covenant units) of the amount of methane left in the Grunt's pack. When the tank gets low, a resupply of methane must be found quickly, or the Grunt will suffocate. The suit also has the color of the grunts rank on display. In Halo 3, both the breathing mask and backpack component of the suit can be knocked off; this causes the Grunt to suffocate.

Defense
In addition to its life support role, it is equipped with armor. This armour can withstand limited amounts of fire, especially from energy weapons. The M6D is capable of easily cracking through the armour, and is considered by some to be the standard weapon for such actions. The armour-piercing rounds of the Assault Rifle are also potent weapons against the harness. As well as defending against projectiles and plasma, it prevents a limited amount of fall damage to its user, like its counterpart. Despite this, most variants are vastly inferior to the other types of armour used by the Covenant. Some variants are also equipped with helmets and Active Camouflage.