Covenant supply case
From Halopedia, the Halo wiki
These crates are used by the Covenant to either move cargo or to store weapons, much like the gun shelves on Cairo Station. On Installation 04 the more prepared Covenant have these crate locked from human activities, however on Installation 05 and High Charity the rebellion and the Flood leave these containers open. They carry Plasma Rifles and any covenant weapon except the Fuel Rod Cannon and it is widely thought the Covenant have a recharge device on these crates making them essential to the Covenant. The crates are nearly identical to the Uplink Crates and possibly are part of them. In the novels, namely The Flood, have also been know to hide in crates and surprise those who open them, requiring inspections on all crates.
In Halo 3, the crates do contain Fuel Rod Guns, as well as the Jiralhanae (Brute) Spiker and Mauler.
Dimensions
Height: 1.82 meters (9.22 feet)
Overview
The Covenant Supply Case has appeared throughout the Halo series as a device that has stored the weapons for Covenant encampments. It holds four hand held sized weapons, or just of two larger weapons. It has been speculated that it also acts as a device to recharge plasma based weaponry, as all weapons found in it have been fully charged, but this may just be circumstantial.
Each weapons holder seems to be designated to a particular weapon, as you never see more then one type of weapon being held in a single weapons holder.
Common weapons held by Covenant Weapons Holders include but are not limited to: Plasma Rifles, Particle Beam Rifles, Brute Plasma Rifles, Brute Spikers, and Covenant Carbines.
