Armor customization

Armor Permutations are a feature in Halo 3, allowing the player to aesthetically customize their multiplayer character.

Introduction
Armor Permutations allow a player to customize his/her multiplayer character as either a UNSC SPARTAN-II or a Covenant Elite, and change between different helmets, shoulder pads, chest armor, and detailed colors (primary color, secondary color, and armor detail). All permutations are aesthetic only and do not change actual gameplay.

They were originally discovered in the Halo 3 Beta hexadecimal codes by modders and were later confirmed to provide high levels of player customization by GamePro's June magazine issue. Calculated together, there are 187,947,000 combinations for the player to choose from.

Armor Permutations are available only in Halo 3 (in the earlier parts there is only Mark VI Spartan Armor and CQB Spartan Armor), and are unlocked by achievements in either the Campaign or multiplayer modes of Halo 3 or by getting the skulls.

SPARTAN Armor Permutations

There are a wide variety of SPARTAN II armor permutations, with 11 helmets, 8 shoulder pieces, and 8 chest pieces for a total of 6,144 different SPARTAN armor permutation combinations: one helmet, two shoulder pieces, and chest piece per permutation. Another really cool armour is the flaming one.

Helmets

 * Mark VI: Default Unlocked.
 * CQB: Default Unlocked.
 * EVA: Unlock either Campaign Complete: Normal, Campaign Complete: Heroic or Campaign Complete: Legendary achievements.
 * EOD: Unlock the Campaign Complete: Legendary achievement.
 * Hayabusa: Collect all Skulls.
 * Security:(Marathon Helmet) Get 1000 of 1000 gamerscore in Halo 3. (Getting all Halo 3 achievements)
 * Scout: Unlock the Used Car Salesman achievement.
 * ODST: Unlock the Spartan Graduate achievement.(Online only)
 * Mark V: Unlock the UNSC Spartan achievement.(Online only)
 * Rogue: Unlock the Spartan Officer achievement.(Online only)
 * Recon: Bungie employees, winners of tournaments/double exp weekends, and those that impress (or amuse) Bungie in any other way.
 * Flaming Helmet: Bungie Employees only. Rather than the actual helmet generating the flaming effect, it is a unique chest piece that can reproduce the effect on any helmet. Bungie did state that they may release details on how to get this permutation in their podcast.

Shoulder Pieces

 * Mark VI: Default Unlocked.
 * CQB: Default Unlocked.
 * EVA: Beat the level The Ark on Normal, Heroic, or Legendary difficuties.
 * EOD: Beat the level The Ark on Legendary difficulty.
 * Hayabusa: Collect at least 9 skulls.
 * Security: Get 750 of 1000 gamerscore on Halo 3. Due to inconsistency, this armor permutation is not always given at 750, whereas there are some reports that the Security Shoulders need a minimum of 800 gamerscore, but the official guide to Halo 3 lists the requirements as 750.
 * Scout: Unlock the Mongoose Mowdown achievement. (online)
 * Recon: Bungie employees, winners of tournaments/double exp weekends, and those that impress Bungie in any other way.

Chest Armor

 * Mark VI: Default Unlocked.
 * CQB: Default Unlocked.
 * EVA: Complete Tsavo Highway on Normal, Heroic, or Legendary difficulty.
 * Hayabusa: Collect 5 skulls.
 * Katana (Add-On): Get all achievements in Halo 3. (''Note, Katana is a sword on the back of your armor. Not a chest plate.)
 * EOD: Beat the level Tsavo Highway on Legendary difficulty.
 * Scout: Unlock the Too Close to the Sun Achievement.
 * Recon: Bungie employees, winners of tournaments/double exp weekends, and those that impress Bungie in any other way.
 * Bungie: You must make one scarab destroy another in The Covenant under Legendary difficulty or impress bungie in some way.

Sangheili Armor Permutations
There are a wide variety of Elite armor permutations, with 5 helmets, 5 shoulder pieces, and 5 chest pieces for a total of 625 different Elite armor permutation combinations: one helmet, two shoulder pieces, and chest piece per permutation. Some players think that the Sangheili players have been shortchanged when it comes to armor variants.

Helmets

 * Combat: Default Unlocked.
 * Assault: Default Unlocked
 * Flight: Unlock either Campaign Complete: Heroic or Campaign Complete: Legendary achievements.
 * Ascetic: Unlock the Steppin' Razor achievement.
 * Commando: Unlock the Overkill achievement.(Must be on a Ranked Match online in order to get achievement.)

Shoulder Armor

 * Combat: Default Unlocked.
 * Assault: Default Unlocked.
 * Flight: Beat the level The Ark on Heroic or Legendary difficulties.
 * Ascetic: Unlock the Overkill achievement.
 * Commando: Unlocked automatically after Auto Update 1 was applied on February 19, 2008. Originaly, the Killing Fenzy achievement would unlock this armor permutation.

Body Armor

 * Combat: Default Unlocked.
 * Assault: Default Unlocked.
 * Flight: Beat the level Tsavo Highway on Heroic or Legendary difficulties.
 * Ascetic: Unlock the Up Close and Personal achievement.
 * Commando: Unlock the Triple Kill achievement.(Must be on a Ranked Match online in order to get achievement.)

Unlocking Permutations
Note: The Arbiter's armor cannot be unlocked. 300px All of the armor permutations.

FLAMING HELMET LINK: http://www.youtube.com/watch?v=Il0a_fKuOJQ&feature=related