From Halopedia, the Halo wiki
EMG is a human company that manufactures electrical devices such as the EMG 2401.
In 2552 products of this company were present in the UNSC military base Crow's Nest and the Quito Space Tether, among others.
In 2556, EMG was "Flagged for Review" by ONI after the Sedra terrorist attack.
"EMG 2401", a piece of equipment by EMG.