Photoreactive panels are a form of active camouflage developed by the United Nations Space Command. The outer layer of the Semi-Powered Infiltration armor is coated with photoreactive panels to hide the wearer from sight. While not as sophisticated as Covenant active camouflage, the technology advanced during the Human-Covenant war, with the newer SPI generation being fitted with more efficient photoreactive panels in 2551. Dr. Catherine Halsey also mentioned ODSTs testing this kind of armor.