Flak Jacket

Flak Jacket is a Tier 2 perk featured in Call of Duty: World at War and a Tier 1 perk featured in Call of Duty: Black Ops which reduces explosive damage dealt to the player.

Call of Duty: World at War
In World at War, it is unlocked at rank one in the "Heavy Gunner" class.

Flak Jacket decreases all explosive damage taken by 25%, and caps the maximum damage taken from any one explosive (excluding a direct hit from a grenade launcher, Bazooka or a tank shell) to 75. In effect, this allows the player to survive any single indirect explosive attack. Players who find themselves constantly killed by Grenades, Bouncing Betties, Tanks, Satchels, Artillery Strikes or M9A1 Bazooka will find this perk to be very useful. This perk has very little effect in Hardcore, due to decreasing HP of players, since the 75 damage cap is far above the maximum health level. Getting stuck with a Sticky Grenade with the Flak Jacket equipped will still result in death.

Tips
This perk is commonly used in Headquarters, Domination and War to prevent being killed by grenades while trying to capture a flag or HQ. It is also especially useful in Search and Destroy, as the enemy will plant Bouncing Betties on the target to kill the player planting the bomb. It can also be helpful when camping in the watchtower on Makin because players will often throw grenades into the tower in hopes of killing the player. It is often used with SMGs or Shotguns, as they can deal high damage even without perks such as Stopping Power.

Call of Duty: Black Ops
Flak Jacket returns as a Tier 1 perk in Black Ops.

Overview
Flak Jacket reduces all incoming explosive damage to 35% of its original value (9% in hardcore game modes). In addition, non-direct impact explosives will never deal more than 75 damage (22.5 in hardcore game modes); this means that a player at full health will not be killed by many explosives. Its pro version reduces all fire damage to 5% of its original damage, making the Flamethrower and Napalm Strike nearly worthless against the player. As an added effect, any thrown grenade picked up by the player will have its fuse set to 2.5 seconds, allowing safe grenade returns.

Flak Jacket gives the player model body armor and a helmet.

Pro Challenges

 * Protected – Survive 10 explosions while using Flak Jacket.
 * Demolished – Plant or defuse 10 bombs in Demolition, Sabotage, or Search & Destroy.
 * Throwbacks – Throw back 5 enemy Frag grenades.

Tips

 * All of Flak Jacket pro's challenges can be easily obtained by playing Demolition, due to the high explosive usage around bomb sites and the ability to plant/defuse bombs multiple times during a match.
 * This perk is very useful in order to survive RC-XD explosions. However, the player can still be killed by one if it is touching him/her while it explodes, or if the player's health is below 75% prior to the explosion.
 * Flak Jacket is preferred by some rushing players, as they are frequently the victims of enemy Claymores. Flak Jacket makes a sensible perk choice for this style of play, as many rushers do not wish to give up Marathon in order to use Hacker in order to spot the claymores. With Flak Jacket, finding and avoiding Claymores isn't an issue as they lose their lethality, meaning a player at full health can rush right through without dying. In some cases, this lack of fear might actually improve a rusher's performance and speed more than the perk Lightweight.
 * Flak Jacket is an ideal perk for players who intend to guard objectives or chokepoints, as enemies will frequently toss grenades in an effort to uproot them. This strategy works even more effectively when paired with the Tactical Mask perk, as this adds protection against Tactical Grenades as well.
 * Bullets from the Chopper Gunner and Gunship killstreaks count as explosives, and thus are affected by Flak Jacket. This makes Flak Jacket a effective perk for an anti-air class, but not as useful as Ghost Pro.
 * This Perk is extremely useful on Nuketown (in any game type), because of the extremely high levels of grenade spamming, and claymore usage. It is also worth noting that other Tier 1 perks, such as Ghost and Lightweight will offer very little benefit here, because of the map's very small size.
 * This Perk is extremely useful if you're bad at tactical games, as it allows you to disregard claymores and grenades. However if you're going to use it for this, you should first consider snapping your disc in half, because nobody wants to deal with your shit.

Trivia

 * The Pro effect of Flak Jacket in Black Ops is the same as the effects of the World at War perk Toss Back
 * Although not an exact match the Flak Jacket has a notable resemblance to the armor worn by the Colonial Marines in the movie Aliens.

Videos
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