CIO-class Mjolnir

The MJOLNIR Powered Assault Armor/CIO (Counter Intelligence Operator) is a variant of the MJOLNIR Powered Assault Armor [GEN2].

Development history
The MJOLNIR/CIO variant was manufactured by Acheron Security and utilized by SPARTAN-IVs and Counter-Intelligence Operators for Intel aquisition and strategic data conveyance deep within enemy territory. It was tested at Gdynia, Acheron Fossae on Mars.

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

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

Halo 5: Guardians
Unlock: REQ pack

List of appearances

 * Halo 4
 * Halo 5: Guardians