Covenant supply case
From Halopedia, the Halo wiki
These crates are used by the Covenant much like the human weapon shelves on the Cairo Station. On Installation 04, the more prepared Covenant had these crates locked from human activities. However, on Installation 05 and on High Charity, these containers were left open. The supply cases can carry any Covenant weapon. The crates are nearly identical to the early Covenant communication nodes, and are possibly modified supply cases. A typical supply case is 1.82 meters, or 5 feet 11 inches, high. Flood Pod infectors have also been known to hide in crates and surprise those who open them, requiring inspections on all crates.
Common weapons held by Covenant weapon holders include, but are not limited to: Plasma Rifles, Beam Rifles, Brute Plasma Rifles, Needle Rifles, Brute Spikers, Covenant Carbines, Energy Swords, Concussion Rifles, Fuel Rod Guns, Plasma Pistols, Brute Shots, Needlers, and Brute Maulers.
A variant of the Covenant comm node bearing resemblance to the supply case has also been observed in use by the Covenant during the Battle of Installation 04. These boxes appear to be upside-down supply cases with a keyboard attachment and three antenna sticking out of the top.