Semi-Powered Infiltration armor



The Semi-Powered Infiltration Armor, colloquially called "SPI Armor", was an armor system used by the United Nations Space Command developed for the Spartan-IIIs. Though more advanced than the ODST Ballistic Body Suits, it was far less advanced and less powerful than the MJOLNIR Armor used by the Spartan-IIs. Its main benefit was that it was drastically cheaper to produce than the MJOLNIR armor. This armor was designed with an emphasis on stealth rather than raw power. It features special photo-reactive panels that mimic the surrounding textures, effectively being the UNSC equivalent to the Covenant Active Camouflage systems. It has been described as part legionnaire mail, part tactical body armor, and part chameleon by both Tom-B292 and Dr. Halsey.

SPI Armor Mark I
The SPI armor Mark I, was used by the Spartan-IIIs of Alpha Company. It featured hardened plates and photo-reactive panels. Though advanced compared to standard UNSC infantry armor, it could only take a few glancing blows before failing. It featured full body armor with an enclosed helmet and HUD, and a supply of breathable atmosphere; though only enough for 7 minutes, compared to the MJOLNIR armor’s endurance of 90 minutes. It is also equipped with a cushioning layer of liquid nanocrystals that provided more ballistic protection than three centimeters of Kevlar diamond weave without the bulk. The featured photo-reactive panels gave the Spartans of Alpha Company active camouflage. The camouflage patterns, however, shifted irregularly and imperfectly, which made the photo-reactive panels unmatched against the Covenant Elites Camouflage technologies. This was because the SPARTAN III program probably didn't allow enough time to get the photo-reactive panels working properly. Another concern was the budget spent in making the suits.

SPI Armor Mark II
The SPI armor Mark II was a more advanced version of the SPI Mark I, first used by the drill instructors of Beta Company and then by the Spartans of Beta Company. They had new photo-reactive coating to boost camouflaging properties. There were also numerous experimental refits to the gel ballistic layers, upgraded software suites, and other functions. Although the new photo-reactive coating could mimic a wide range of EM (Electro-Magnetic) radiation, it was still sensitive to overload, which is why it takes the suit a few moments to reset after a flash-bang or plasma hit for example.

It was proposed in 2537 for Alpha Company, but the request was denied because the armor was over budget. After the "successful" operation of Alpha Company, the Mark II armor was approved for mass production. After the augmentation of Gamma Company, small adjustments were installed into the SPI Armor Mark II.

Advantages

 * 1) The armor is significantly cheaper and easier to mass-produce.
 * 2) Includes special photo-reactive panels that act as an active camouflage for the wearer.
 * 3) It could be transported easily, because it is not as thick or heavy as the MJOLNIR armor.
 * 4) The armor requires less physical enhancements compared to the MJOLNIR armor making it more versatile to other would-be users.

Disadvantages

 * 1) Has no energy shield unlike the SPARTAN-II's MJOLNIR armor.
 * 2) Does not give the SPARTAN-IIIs any enhanced strength, speed or agility as the MJOLNIR does for SPARTAN-IIs.
 * 3) It stresses more on teamwork to take down enemy threats.
 * 4) Since the AC plates take time to recover, after explosions such as a flash bang grenade and plasma hits, the SPARTAN-III is visible until the plates recover.
 * 5) Is made of a less dense alloy than MJOLNIR armour as Kelly-087 managed to dent Holly's chest plate with her fist on the planet Onyx.
 * 6) The SPI armor does not dispel water unlike MJOLNIR armor.
 * 7) The SPI armor can not be used for long periods of time without the cooling system failing.
 * 8) The SPI armor has air for only 7 minutes, the MJOLNIR has air for 90 minutes.
 * 9) The armour is less agile and more clumsy to use.

Trivia

 * Some screenshots released by Bungie lead to fans speculating that they would be able to use SPI armor in Halo 3. However, the armor was later determined to be Mark VI MJOLNIR Powered Assault Armor/V variant. The name and changes in appearance are purely cosmetic, however, having no impact on gameplay. This has been confirmed by Bungie.
 * For all intents and purposes, SPI armor is simply a less-powerful version of MJOLNIR armor. It was meant to give the wearer maximum protection at the minimum cost, so many of the original armor features (for example, shields) were left out.
 * The SPI helmet looks interestingly like the EVA (Mark VI MJOLNIR Powered Assault Armor/V variant) Armor Permutation, the only visible difference is that the faceplate is a bit smaller
 * Kelly-087 first saw this kind of armor worn by ODSTs testing it, possibly much before it came in use by the Spartan-III.

Internal Links

 * Halo: Ghosts of Onyx