Editing Semi-Powered Infiltration armor

{{Status|Canon}}
{{Armor infobox
|name=Semi-Powered Infiltration armor
|image=[[File:HM-SPI-schematic.jpg|275px]]
|manufacturer=[[Watershed Division]]<ref name="HM">'''[[Halo Mythos]]''', ''pages 76-77''</ref>
|testsite=[[Currahee Special Assembly Plant 2]]{{Ref/Reuse|HM}}
|type=
|role=Stealth/assault
|hideb=y
}}
The '''Semi-Powered Infiltration armor''' ('''SPI armor''') is a [[United Nations Space Command]] 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}}

== Overview ==
Described as "part legionnaire mail, part tactical body armor, and part chameleon", the SPI armor features [[photoreactive panel]]s that mimic the surrounding textures, effectively being the UNSC equivalent to the [[Covenant]]'s [[active camouflage]] systems.<ref>'''Halo: Ghosts of Onyx''', ''page 16''</ref> The SPI armor features a full body armor with an enclosed helmet and [[heads-up display]]. The undersuit is equipped with a cushioning layer of liquid nanocrystal that provides more ballistic protection than three centimeters of [[wikipedia:Kevlar|Kevlar]] diamond weave, without the bulk.<ref name="goo171">'''Halo: Ghosts of Onyx''', ''page 171''</ref> The hardened armor plates, though advanced compared to standard UNSC infantry armor, can take only a few glancing blows before failing.{{Ref/Reuse|goo14}}

Though more advanced than the [[Orbital Drop Shock Troopers]]' [[ODST armor|body armor]], the SPI armor is less powerful than the [[MJOLNIR Powered Assault Armor]] originally issued to the [[SPARTAN-II program|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> The cost reduction meant that dozens to hundreds of suits of SPI could be produced for the cost of a single suit of [[MJOLNIR Powered Assault Armor/Mark IV|Mark IV]].{{Ref/Site|Id=CFAA|URL=https://www.halowaypoint.com/en-us/news/anniversary-armory|Site=Halo Waypoint|Page=Canon Fodder - Anniversary Armory|D=24|M=02|Y=2024}} 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>

The SPI armor generally lacks an [[energy shielding]] system, making the user far more vulnerable to enemy fire. However, the Spartan-III [[Headhunters]] wore experimental armor that was equipped with energy shields due to their elite nature and value. However, power must be drawn from the energy shields to recharge the suit's active camouflage module.<ref name="head212">'''[[Halo: Evolutions - Essential Tales of the Halo Universe]]''', "[[Headhunters]]", ''page 212''</ref>

The baseline SPI armor can be easily destroyed from plasma based weaponry, armor piercing rounds and other threats. Overall the armor has inferior protection than [[Mjolnir armor]], forcing the user to rely heavily on its stealth technology and superior tactics.{{Citation needed}}

==Operational history==
Early versions of the Semi-Powered Infiltration armor were developed by [[ONI Section Three]] around the beginning of the [[Human-Covenant War]] for use by ONI agents. A facility dedicated to testing the armor was constructed underground at the future site of the [[Avery J. Johnson Academy of Military Science]].{{Ref/Game|HINF|Site Unseen}}

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.{{Ref/Site|Id=CF50|URL=https://www.halowaypoint.com/en-us/news/canon-fodder-fifty-caliber|Site=Halo Waypoint|Page=Canon Fodder - Fifty Caliber|D=10|M=03|Y=2019}} 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/Reuse|CF50}}

== Versions ==
=== Mark I ===
The Mark I was an 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>

=== Mark II ===
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> Originally, the suits were not watertight,<ref name="GoOCP">'''Halo: Ghosts of Onyx''', Chapter Prologue</ref> but by 2552 they had been upgraded to resist submersion with their own [[oxygen]] supply.<ref name="GoOC28">'''Halo: Ghosts of Onyx''', Chapter 28, page 251</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>

==Mainline armor components==
;MIRAGE-class helmet<ref name="mythos">'''[[Halo Mythos]]''', ''page 77''</ref>: The standard headgear of the SPI armor, the [[MIRAGE-class helmet]] features a large, bulbous faceplate somewhat similar to that of the [[MJOLNIR Powered Assault Armor/V variant|Mjolnir EVA variant]]. The visor is normally gold-mirrored in color<ref name="goo115">'''Halo: Ghosts of Onyx''', ''page 115''</ref> and can be depolarized.{{Ref/Reuse|goo168}} The helmet supports a [[heads-up display]] with features similar to that of the MJOLNIR system, including TACMAP, TEAMBIO, and [[COM|TEAMCOM]] interfaces; a [[motion tracker]];<ref>'''Halo: Last Light''', ''page 146'' (Google Play edition)</ref> as well as team status lights.<ref>'''Halo: Ghosts of Onyx''', ''pages 17, 22''</ref><ref name="g114">'''Halo: Ghosts of Onyx''', ''page 114''</ref> The visor suite features an automatic magnification and image enhancement system controlled by the wearer's eye movements. For example, if the wearer squints while looking at a particular spot the system will automatically zoom in.<ref>'''Halo: Ghosts of Onyx''', ''page 19''</ref> Both the image enhancement and the visor's internal polarization can also be controlled manually.<ref>'''Halo: Ghosts of Onyx''', ''page 268''</ref><ref>'''Halo: Ghosts of Onyx''', ''page 345''</ref> The helmet possesses tactical lights<ref>'''Halo: Ghosts of Onyx''', ''page 273''</ref> and a defogging vent to remove internal moisture.<ref>'''Halo: Ghosts of Onyx''', ''page 316''</ref>

;Techsuit: The bodysuit of the SPI system is composed of a layered mesh of ballistic liquid nanocrystal that is significantly more effective than traditional body armor materials such as Kevlar while being less bulky.{{Ref/Reuse|goo171}}{{Ref/Reuse|g114}}<ref>'''Halo: Ghosts of Onyx''', ''page 360''</ref> The techsuit's leggings<ref name="g141">'''Halo: Ghosts of Onyx''', ''page 141''</ref> and sleeves can be removed independently.<ref>'''Halo: Last Light''', ''page 125'' (Google Play edition)</ref>

;Photoreactive panels: The outer shell of the SPI armor comprises a series of lightweight laminate plates with a photoreactive coating.{{Ref/Reuse|HM}} The photoreactive panels act as [[active camouflage]] when active,<ref>'''Halo: Ghosts of Onyx''', ''page 165''</ref> effectively blending the wearer with their environment.{{Ref/Reuse|goo14}} The coating also renders the wearer nearly invisible to infrared and passive light-gathering systems.<ref>'''Halo: Last Light''', ''page 95'' (Google Play edition)</ref> Since the photoreactive plates take time to recover after explosions such as a [[flashbang grenade]] and [[Plasma weaponry|plasma]] hits, the wearer is visible until the plates recover.{{Ref/Reuse|goo113}} With the exception of the [[Headhunters]]' suits, the SPI armor does not feature energy field-based active camouflage systems like those of the Covenant.{{Ref/Reuse|head212}} When inert, the plating is matte gray{{Ref/Reuse|mythos}}{{Ref/Reuse|g141}} or green, though some SPI suits have been known to use different colors such as red.<ref>'''Headhunters''' ''motion comic''</ref><ref>'''Halo Mythos''', ''page 135''</ref>

;Rift-class gauntlets: The SPI suit is equipped with shock-resistant and force-amplifying [[Rift-class gauntlets]].{{Ref/Reuse|HM}}

;Tactile bracers: The bracer armor pieces around the boots grant slight improvements to speed and dexterity with negligible shielding reduction.{{Ref/Reuse|HM}}

;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> The armor also has an efficient cooling system and is significantly difficult to detect even with thermal scanners.{{Ref/Reuse|goo89}}

;Biofoam injection ports: Like MJOLNIR, the SPI armor has dedicated ports allowing the quick injection of [[biofoam]] or other battlefield pharmaceuticals.<ref>'''Halo: Ghosts of Onyx''', ''page 362''</ref>

;Data socket: The SPI armor's gauntlet features a data port to which small electronic devices such as [[data pad]]s can be connected.<ref>'''Halo: Ghosts of Onyx''', ''page 310''</ref><ref>'''Halo: Ghosts of Onyx''', ''page 356''</ref>

;Power cell: The armor is powered by a low-profile, shielded [[BA-55901/PLMD]] battery cell.{{Ref/Reuse|mythos}}

==Variants==
In addition to the standard model, several variants of the SPI armor exist.{{Ref/Note|Similar to the somewhat differing depictions of [[Mjolnir armor]], the exact design details of the "default" SPI armor vary between different sources of ''Halo'' canon, sometimes within a single source. Since it is difficult to determine which of these examples constitute officially-defined variants of the suit rather than artistic license, only the versions that overtly deviate from the standard pattern are listed below, while the gallery section provides examples of less pronounced variety between SPI suits.}}

===Air Assault-like===
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]] and equipped with motion trackers, energy shielding, VISR, and a prototype active camouflage.
<gallery>
File:Roland SPI 2.png|Air Assault-like.
</gallery>

===Pilot-like===
This variant has a helmet design that is similar to [[PILOT-class Mjolnir|Pilot]]. A Spartan-III wearing this variant was stuck in Onyx between 2552 and 2553.
<gallery>
File:Mythos SPI red version.jpg|Pilot-like helmet.
</gallery>

===Grenadier-like===
This variant has a helmet design that is similar to [[GRENADIER-class Mjolnir|Grenadier]]. [[Mark-G313]] wore this suit during [[Operation: JOVIAN WHISTLE]].{{Ref/Note|In [[:File:Halo Last Light cover.jpg|the cover]] of ''Halo: Last Light'', Mark (who is seen in the background of the image) is depicted as wearing a standard set of SPI armor.}}
<gallery>
File:Marksniper.png|Grenadier-like.
File:Enc22 MarkG313.jpg|The suit.
</gallery>

===Mirage===
{{Main|MIRAGE-class Mjolnir}}
This variant is a modified SPI armor and compatible with the [[MJOLNIR Powered Assault Armor]] [[MJOLNIR Powered Assault Armor/Mark VI|Mark VI]]. It incorporates the latest in software-definable deception jammers, and the forearms are a further refinement of the RIFT-class force-amplification gauntlets found on the standard SPI armor.
<gallery>
File:HTMCC Mirage Armour.jpg|MIRAGE-class Mjolnir
</gallery>

==Non-canon and dubious canon appearances==
[[File:HTVS2 - KaiWithSPIRegiment.png|thumb|right|250px|SPI-clad SPARTAN-IIIs in front of [[Kai-125/Silver|Kai-125]].]]
===Silver Timeline===
{{Notice/Silver|category=no}}
{{Quote|Nice suit.|[[John-117/Silver|John-117]] commenting on [[Talia Perez]]'s SPI armor.{{Ref/Film|Id=Thermopylae|TV|Episode=[[Thermopylae (TV Series)|Thermopylae]]}}}}
{{Expand-section}}
{{Clear}}

==Production note==
{{Linkbox|gallery=yes|gallerypage=Images of SPI Armor}}
The SPI armor is referred to as "PR" twice in ''Halo: Ghosts of Onyx''.<ref>'''Halo: Ghosts of Onyx''', ''page 87'' (''"...the flaws in their Mark-I PR suits..."'')</ref><ref>'''Halo: Ghosts of Onyx''', ''page 141'' (''"...and pulled on the PR leggings."'')</ref> No context or explanation is provided for this alternate designation, although it is possible that the suit was known as "PR" (possibly an acronym for "PhotoReactive") in an earlier revision of the novel's manuscript and that the presence of the two mentions in the final book is an editing oversight.

== Gallery ==
<gallery>
File:HGOO Kurt Crop.jpg|Kurt-051 wearing SPI armor in ''[[Halo: Ghosts of Onyx]]''.
File:Semi-Powered Infiltration.png|A conceptual illustration of the SPI armor.
File:H3 Guardian Mirage AR.png|A [[Spartan-II]] clad in [[MIRAGE-class Mjolnir]] in the ''[[Halo 3]]'' portion of ''[[Halo: The Master Chief Collection]]''.
File:Headhunters.png|Two Headhunters, [[Roland-B210]] and [[Jonah-B283]], wearing SPI armor in ''[[Headhunters (story)|Headhunters]]''. 
File:Spivariant.jpg|Another view of Roland's and Jonah's SPI armor.
File:HEvol - SPI HUD.png|An energy shielded SPI suit's [[Heads-up display|HUD]]. Note the HUD's resemblance to that of the [[MJOLNIR Powered Assault Armor/Mark V|MJOLNIR Mark V]].
File:Headhunter SPI Armor.jpg|[[Jonah-B283]] wearing his SPI armor.
File:Headhunters - Jonah profile.png|Renders of Jonah's SPI armor.
File:Evo Headhunters Post.jpg|Officially endorsed fan art of Jonah and Roland wearing modified SPI armor.
File:HLL cover-Olivia full.png|[[Olivia-G291]] in SPI armor with her helmet removed in ''[[Halo: Last Light]]''.
File:HM-SIIIs.png|MIRAGE-class helmet with an eagle emblem on the visor in ''[[Halo Mythos]]''.
File:HM EVA-like SPI.png|EVA-like helmet stylized SPI. 
File:TfS - SPARTAN-G059.png|[[SPARTAN-G059]] clad in SPI armor in ''[[Knight Takes Bishop]]''.
File:Veta SPI.png|[[Veta Lopis]] equipped with SPI armor in ''[[Halo: Retribution]]''.
File:HINF Mirage IIC Core Icon.png|The Mirage IIC core in ''[[Halo Infinite]]''.
File:Enc22 Kurt with helmet.jpg|Image of Kurt Ambrose clad in SPI from the ''[[Halo Encyclopedia (2022 edition)|Halo Encyclopedia]]''.
File:Enc22 SPI.png|An image of SPI armor in the ''Halo Encyclopedia''.
File:HTVS2-SpartansinSPI.jpg|SPI-clad Spartan-IIIs in ''[[Halo: The Television Series Season Two]]''.
</gallery>

== List of appearances ==
*''[[Halo: Ghosts of Onyx]]'' {{1st}}
*''[[Halo 3]]'' {{C|''Halo: The Master Chief Collection'' only}}
*''[[Halo: Evolutions]]''
**''[[Headhunters (short story)|Headhunters]]''
*''[[Halo: Reach]]'' {{Mo}}
*''[[Halo: Glasslands]]''
*''[[Halo: Last Light]]''
*''[[Halo Mythos]]''
*''[[Halo: Tales from Slipspace]]''
**''[[Knight Takes Bishop]]''
*''[[Halo: Retribution]]''
*''[[Halo: Official Spartan Field Manual]]''
*''[[Halo: Divine Wind]]'' {{Mo}}
*''[[Halo Infinite]]''
**''[[Season 03: Echoes Within]]''
*''[[Halo: The Television Series Season Two]]''
**''[[Aleria (TV Series)|Aleria]]''
**''[[Onyx (TV Series)|Onyx]]''
**''[[Thermopylae (TV Series)|Thermopylae]]''
**''[[Halo (TV Series)|Halo]]''

==Notes==
{{Ref/Notes}}

== Sources ==
{{Ref/Sources|2}}

{{Armor|Human}}
[[Category:Armor]]