The Phazon Suit is an upgrade to Samus Aran's Power Suit acquired in Metroid Prime. While other suit upgrades involve the incorporation of advanced technological hardware, the Phazon Suit was the inadvertent result of the Power Suit being virally corrupted by Phazon upon defeating the Omega Pirate.
The most distinguishing feature of the Phazon Suit was its uniquely dark color scheme: The armor covering the arms, legs and shoulders was entirely glossy black, while the helmet, torso and inner thighs were a dark silver-grey. Its visor was a bright orange, while the lights on the suit were crimson. Strangely, the Phazon Suit also emitted a slight aura that distorted the air around it, most likely due to radiation or the strength of it's defensive shielding.
The Phazon Suit provided 50% damage reduction, the greatest level of defensive shielding in Metroid Prime. It also made Samus immune to radiation from blue Phazon, but offered no protection from the more lethal red Phazon strain. Finally, the suit could channel pure Phazon into itself and enter a state called Hyper-mode, which not only covered Samus' entire body with a blue aura, but also caused the emergence of blue veins on her right shoulder and radically transformed her Arm Cannon to fire the most powerful weapon in the game: the Phazon Beam.