Mark I Powered Exoskeleton
From Halopedia, the Halo wiki
The Mark I powered exoskeletons were a precursor to the MJOLNIR armor project.
The armor allows the wearer to run at over 32 KPH (19.872 MPH), lift two tons, and have a 30mm minigun mounted on self-targeting armatures. They are equipped with motion sensors and IR scopes. The armor is impervious to standard light weapons. Nine people in powered exoskeleton suits can easily hold their own against two or three platoons of Marines.
The model had to be scrapped and redesigned from the ground up for MJOLNIR. They consumed enormous energy. Either they had to be plugged into a generator or use inefficent broadcast power. Neither of these options were practical on a battlefield.
They used units of these that were not scrapped as dock loaders or to move heavy equipment. Some were even used for mining, then thrown into storage on Reach.
After their augmentation procedures, Chief Petty Officer Mendez ordered the trainers of the Spartans to use powered exoskeletons when in combat exercises with them. Otherwise, the training may have killed those trainers, as evidenced by SPARTAN-117's accidental killing of three ODST's aboard the UNSC Atlas. The Spartans easily overcame the cumbersome armor, however. The armor just did not match up to the superior speed and stealth of the Spartans.
