From Halopedia, the Halo wiki
HAZOP-class Mjolnir (Hazard Operability), is a MJOLNIR Powered Assault Armor, is a MJOLNIR armor variant originally designed by the Materials Group, with the GEN2 version being manufactured by Acheron Security.
The HAZOP armor utilizes a specialized material that helps protect the user from heightened exposure to radiation that normal Mjolnir suits cannot. HAZOP also employs biothreat filters and corrosion-resistant sealing valves that operate in synchronicity, which is a unique technology to process and manufacture oxygen in highly toxic conditions.
Early on in the Human-Covenant War prototypes of the suits were created for use for where the UNSC had to battle the Covenant head on in environments that were chemically volatile for average Mjolnir suits.
The helmet has a view-path stabilizing visor with AZ-T sensor array, with a modified rebreather castor lines. The chest contains a redundant oxygen filtration system (Unit A-7X43), with the reactor pack in a firm-case fusion pack to simplify withdrawal process. The armor also has the most advanced radiation shielded underarmor mesh currently in production by the UNSC.
Templates for the GEN2 were acquired by Acheron Security from the Materials Group in 2553, where a number of advances were engineered to enhance protective operability during EVA deployment while outside a vehicle in slipspace.
Acheron Security re-architected the GEN2 HAZOP-class armor systems explicitly for extended operations within exotic and environmentally hazardous locales.
While its process of operability during EVA deployment while outside a vehicle in slipspace is slow, many Spartans have adopted the framework of HAZOP.
Halo: Reach - GEN1
Halo 4 - GEN2
HAZOP was one of the armor permutations to return, albeit completely redesigned for GEN2, in Halo 4. In The Master Chief Collection, the HAZOP set and its Forest (FRST) skin variant are available by default.
Halo Infinite - Upgraded GEN1
The Mark V HAZOP helmet and its attachments are available for multiplayer Spartan armor customization on the Mark V [B] armor core in Halo Infinite. The HAZOP shoulders are available under the SAP series of shoulder pads.
List of appearances