Complete the task in Campaign mode to unlock the corresponding armor part in multiplayer.

Elite Ascetic Body - Earn the "Up Close and Personal" achievement.
Elite Ascetic Head - Earn the "Steppin' Razor" achievement.
Elite Ascetic Shoulders - Earn the "Overkill" achievement.
Elite Commando Body - Earn the "Triple Kill" achievement.
Elite Commando Head - Earn the "Overkill" achievement.
Elite Commando Shoulders - Earn the "Killing Frenzy" achievement.
Elite Flight Body - Complete "Tsavo Highway" under the Heroic or Legendary difficulty.
Elite Flight Head - Complete Campaign mode under the Heroic difficulty.
Elite Flight Shoulders - Complete "The Ark" under the Heroic or higher difficulty.
Spartan EOD Body - Complete "Tsavo Highway" under the Legendary difficulty.
Spartan EOD Head - Complete Campaign mode under the Legendary difficulty.
Spartan EOD Shoulders - Complete "The Ark" under the Legendary difficulty.
Spartan EVA Body - Complete "Tsavo Highway" under the Normal or higher difficulty.
Spartan EVA Head - Complete Campaign mode under the Normal or higher difficulty.
Spartan EVA Shoulders - Complete "The Ark" under the Normal or higher difficulty.
Spartan Mark V Head - Earn the "UNSC Spartan" achievement.
Spartan ODST Head - Earn the "Spartan Graduate" achievement.
Spartan Rogue Head - Earn the "Spartan Officer" achievement.
Spartan Scout Body - Earn the "Too Close to the Sun" achievement.
Spartan Scout Head - Earn the "Used Car Salesman" achievement.
Spartan Scout Shoulders - Earn the "We're in for Some Chop" achievement.
Spartan Security Head - Earn 1,000 Gamerscore points.
Spartan Security Shoulders - Earn 250 Gamerscore points.