Editing Semi-Powered Infiltration armor

The '''Semi-Powered Infiltration armor''' ('''SPI armor''') is a [[UNSC]] combat [[armor]] system designed with an emphasis on stealth through the use of [[photoreactive panel|special photoreactive panels]].<ref name="goo14">'''[[Halo: Ghosts of Onyx]]''', ''page 14''</ref> The armor was developed by the [[Watershed Division]], with [[Ruk Ariaustin]] as design lead.{{Ref/Reuse|HM}}

Though more advanced than the [[Orbital Drop Shock Troopers]]' [[ODST armor|body armor]], the SPI armor is less powerful than the [[Mjolnir armor]] originally issued to the [[Spartan-II]]s.<ref>'''[[Halo: Glasslands]]''', ''page 207''</ref> Its main benefit is that it is drastically cheaper to produce than Mjolnir.<ref name="goo46">'''Halo: Ghosts of Onyx''', ''page 46''</ref> Although the SPI suit provides modest enhancements to the wearer's strength and mobility,{{Ref/Reuse|HM}} this amplification is not as drastic as that afforded by the Mjolnir.<ref>'''Halo: Last Light''', ''page 33'' (Google Play edition)</ref> Consequently, the SPI armor can be worn by any individual and does not require special neurological, skeletal or muscular [[Biological augmentation|augmentation]]; for example, the unaugmented instructors for the Spartan-IIIs often wore SPI armor.<ref>'''Halo: Ghosts of Onyx''', ''pages 89, 94''</ref>{{Ref/Reuse|g164}} The SPI armor is not as bulky or as heavy as the Mjolnir armor,<ref>'''Halo: Glasslands''', ''page 40''</ref> although the plating material is also less durable: [[Kelly-087]] dented a Spartan-III's chest plate with her fist when first encountering the Spartan-IIIs.<ref name="goo168">'''Halo: Ghosts of Onyx''', ''pages 168-169''</ref>

Although early versions of the SPI system were tested by [[Orbital Drop Shock Troopers]],<ref name="g164">'''Halo: Ghosts of Onyx''', ''page 164''</ref> the armor was most prominently issued to the [[Spartan-III]] supersoldiers.{{Ref/Reuse|goo14}} With over 2,000 units of SPI armor manufactured during the [[Human-Covenant War]],{{Ref/Reuse|HM}} the SPI armor had been mostly phased out of use by Spartan-IIIs by [[2558]] in favor of Mjolnir. However, SPI continues to fill a usage niche in covert roles, particularly within ONI; the Spartan-IIIs in [[Veta Lopis]]' [[Ferret]] team often used SPI instead of Mjolnir due to the former's superior stealth capabilities.<ref>''Halo: Retribution'', Chapter 18</ref><ref>[https://twitter.com/TDenningauthor/status/912699859924393984 '''Twitter''': ''Troy Denning status update #912699859924393984'']</ref> The SPI armor has also been issued to non-Spartan personnel, such as Veta Lopis, whose suit was custom-built to fit her small frame.<ref>[https://twitter.com/TDenningauthor/status/879779858393440256 '''Twitter''': ''Troy Denning status update #879779858393440256'']</ref> [[SPARTAN-G059]], deployed as an ONI assassin, used SPI as late as 2558.<ref>'''[[Halo: Tales from Slipspace]]''', ''[[Knight Takes Bishop]]''</ref> As well, the photoreactive plating technology has seen limited but successful use in several special operations ODST units.<ref>[https://www.halowaypoint.com/en-us/news/canon-fodder-fifty-caliber '''Halo Waypoint''' - ''Cannon Fodder: Fifty Caliber'']</ref>

The Mark I was the first, experimental iteration of the SPI system used by the Spartan-IIIs of [[SPARTAN-III Alpha Company|Alpha Company]]. The featured photoreactive panels gave the Spartans of Alpha Company a rough equivalent to active camouflage. The camouflage patterns, however, shifted irregularly and imperfectly, which made the photoreactive panels inferior compared to the [[Covenant]]'s active camouflage technologies.<ref>'''Halo: Ghosts of Onyx''', ''page 85''</ref>

The Mark II was an improvement of the SPI Mark I, first used by the drill instructors of [[SPARTAN-III Beta Company|Beta Company]], and then by the Spartans of Beta and Gamma Companies.<ref name="goo89">'''Halo: Ghosts of Onyx''', ''page 89''</ref> The armor sports new photoreactive coating to boost its camouflaging capabilities. Although the new photoreactive coating can mimic a wide range of electromagnetic radiation, it is still sensitive to overload, making the wearer vulnerable for several seconds after a [[flashbang]] or [[plasma]] shots from plasma weaponry or any directed energy weapon hit while the panels reset.<ref name="goo113">'''Halo: Ghosts of Onyx''', ''page 113''</ref>

The armor was proposed by [[Kurt Ambrose]] in [[2537]] for Alpha Company, but the request was denied because the armor was over budget.<ref>'''Halo: Ghosts of Onyx''', ''page 80''</ref> After Alpha Company's Pyrrhic victory in [[Operation: PROMETHEUS]], the Mark II was approved for mass production. After the augmentation of [[SPARTAN-III Gamma Company|Gamma Company]], small adjustments were installed into the Mark II SPI armor,{{Ref/Reuse|goo99}} including experimental refits to the ballistic gel layers, upgraded software suites, and other functions, slated to be introduced to the systems prior to Gamma Company's deployment in [[2552]].<ref name="goo99">'''Halo: Ghosts of Onyx''', ''page 99''</ref> One major improvement is that the armor is now hermetically sealed and contains an internal [[oxygen]] supply for seven minutes.<ref name="g251">'''Halo: Ghosts of Onyx''', ''page 251''</ref>

;Environmental controls: The suit possesses rudimentary environmental regulation system to maintain a comfortable temperature for the wearer.<ref>'''Halo: Ghosts of Onyx''', ''page 22''</ref> However, the system is not designed for extended use and it will become increasingly uncomfortable to wear if used continuously over long periods of time.<ref>'''Halo: Ghosts of Onyx''', ''page 254''</ref> As of 2552, the Mark II SPI armor is also fully sealed and contains an internal oxygen supply.{{Ref/Reuse|g251}} The armor also has an efficient cooling system and is significantly difficult to detect even with thermal scanners.{{Ref/Reuse|goo89}}

This variant has a [[STALKER-class Mjolnir|Stalker]]-like suit, with a helmet that is similar in design to [[AIR ASSAULT-class Mjolnir|Air Assault]]. It was utilized by [[Roland-B210]]. It was equipped with Motion trackers, energy shielding, VISR technology and a prototype active camouflage.

File:HINF SPI armor core teaser.png|The Mirage IIC core in ''[[Halo Infinite]]''.