From Halopedia, the Halo wiki
The MIRAGE armor takes the form of SPI suits designed for the SPARTAN-III program, upgraded to MJOLNIR standards intended to be employed by any Spartan generation. Once the standard helmet of SPI armor, MIRAGE-class Mjolnir makes use of an upgraded MIRAGE-class helmet. The gauntlets are designed as a refinement of the RIFT-class force amplification gauntlets. Overall, the suit is light and resilient, though considered not as robust as the MJOLNIR program's efforts. However, it is able to be manufactured at a fraction of the price while meeting the same basic performance requirements.
Mirage was implemented into Halo 3 in the 20th anniversary celebration event for Halo: The Master Chief Collection. The set is available for purchase in The Exchange on the week of November 24, 2021.
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