Covenant power module
From Halopedia, the Halo wiki
These modules are used to provide power within any major Covenant structure or possibly even ships. Some of these modules are known to be stored in Deployment spires. Should the UNSC obtain a power module, it would allow them to reverse-engineer the Covenant technology and provide them the necessary information to improve their own technology.
These modules are strikingly similar to plasma batteries in style. The shape itself is much like a thick dumbbell. There are small bars for holding when a module needs to be transported on foot. Although similar to plasma batteries, these modules do not explode when shot.
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