From Halopedia, the Halo wiki
EXO/TSCS is an armor attachment that is compatible with MJOLNIR Mark V. EXO/TSCS is well-suited for exo-atmospheric engagements, and features an on-board Tactical Signals Intelligence Collection System.
The chest piece consists predominantly of a dark gray metal collar encircling the user's neck, set upon a thicker armored base that connects to the existing the Mjolnir Mark V chest piece upon which it is layered. The two sides of the collar are cut off beneath the user's chin, and therefore do not meet to create a full circle. Instead, the armored base on each side extends downward along the user's chest, forming two parallel strips which are joined at the sternum by a small connecting segment.
The chest piece that would later become known is one of a handful of cut armour sets intended to be included within the release of 2011's Anniversary Map Pack. The chest was first revealed in promotional screenshots for the map pack, though usually obscured behind weapons and character positions. The chest was later revealed as being included in the early Flighting files for Halo: The Master Chief Collection on PC, though little was confirmed of the armour's status until late 2020 when it was officially confirmed to be included in Season 4: Reclaimer. Production issues ultimately pushed the release of EXO/TSCS back to the January 2021 release of Season 5: Anvil.
Defiant Map Pack promotional images
Halo: The Master Chief Collection datamined models
Halo: Reach MCC screenshots
List of appearances