The Methane is stored in extremely cold tanks inside the suit, and is provided to the user through a breathing mask that covers over half of the alien's head. The backpack attached to an Unggoy's back contains a Methane Tank. Attached to every Unggoy's wrist is a readout (measured in Covenant units) of the amount of methane left in the Unggoy's pack. When the tank gets low, a resupply of methane must be found quickly or the Unggoy will suffocate. The suit also displays the color of the Unggoy's rank. The breathing mask of the Unggoy also makes speech difficult for them, as it muffles their words.