CIO-class Mjolnir

CIO-class Mjolnir (Counter Intelligence Operator) is a variant of the MJOLNIR Powered Assault Armor [GEN2] manufactured by Acheron Security.

Overview
The CIO helmet has a tricloptically fixed multi-spectral imaging array, also known as a transponder array. The neural interface bypasses in the CIO helmet allow the wearer to create custom synesthesis profiles to remap the suit sensors with their own senses. The suit also has a galvanized sensory suite that rivals nearly all other similar service packages.

The chest has a modular sensory suite, and a silhouette dampener for motion sensor circumvention.

Development history
After seeing the need for highly trained, heavily armored personnel to be deployed deep into enemy-controlled territory, Acheron Security developed and manufactured the CIO-class armor, with its main focus on espionage rather than lethality. The armor was tested at the Acheron Trauma Sim, and was designed to operate in the Martian territory of Acheron Fossae.

Usage
Though rarely seen, it is utilized by a handful of SPARTAN-IVs and Counter-Intelligence Operators for intel acquisition and strategic data conveyance deep within enemy territory, often those who endure tier-nine theaters.

Several CIO-armored Spartans were deployed to Terceira, where they captured and transmitted information crucial to the recovery of the colony from Insurrectionist forces.

CIO is also used during information denial missions, hunting down enemy scouts and preventing them from acquiring data of tactical or strategic importance.

Halo 4
Available skins: Web (WEB), Ruin (RUIN), and Rush (RUSH) Default unlock: Complete the Spartan Slayer - Master commendation Web unlock: The Web skin was a pre-order bonus through Amazon. It is also available in the Halo 4 Game of the Year Edition. Ruin unlock: Purchase the CIO-armored Spartan action figure in the second series of McFarlane's Halo 4 action figures. This is not usable in Spartan Ops. Rush unlock: Purchase the Champions Bundle. This is not usable in Spartan Ops.
 * Description: Designed for counter-intelligence operability in the Martian territory of Acheron Fossae.

Halo 5: Guardians
Unlock: Rare REQ card
 * Helmet description: The neural interface bypasses in the CIO helmet allows the wearer to create custom synesthesis profiles to remap the suit sensors with their own senses.
 * Body description: CIO's niche is information denial missions: hunting down enemy scouts and preventing them from acquiring data of tactical or strategic importance.

In Halo 5: Guardians due to the "Body" having a predefined customisation this armor set permanently has the following parts from Halo 4:
 * Body: CIO
 * Shoulders: CIO
 * Forearms: Ricochet
 * Legs: Recruit

List of appearances

 * Halo 4
 * Infinity Briefing Packet
 * Halo 5: Guardians