Semi-Powered Infiltration Armor

The Semi-Powered Infiltration Armor, colloquially called "SPI Armor", was an armor system 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 lesser equivalent to the more advanced Active Camouflage systems. It has been described as part legionnaire mail, part tactical body armor, and part chameleon.


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 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 advanced Camouflage technologies.


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.


Advantages of SPI Armor
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. It is more flexible to move by will of the wearer.
5. The armor requires less physical enhancements compared to the MJOLNIR armor making it more versatile to other would-be users.

Disadvantages of SPI Armor
1. Has no energy shield unlike the SPARTAN-II's MJOLNIR armor.
2. Does not give the SPARTAN-IIIs the same amount of enhanced strength, speed, and agility as the MJOLNIR does for SPARTAN-IIs.
3. It stresses more teamwork on the Teams 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 armor.
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.