Semi-Powered Infiltration Armor Suits(SPI Armor) was developed by ONI Section Three, for use by SPARTAN-IIIs. It was made to be much cheaper than the MJOLNIR armor worn by SPARTAN-IIs, and has built in active-camo. The suit doesn't increase the wearer's speed or strength, and has no energy shields like MJOLNIR armor.
I made the helmet with a Mega Bloks astronaut faceplate glued to a blue helmet. I'm currently working on aking him scale to other minifigs, and decals.