Tier 2 perks are the second set of perks a user can choose. This group is red. There are five different perks: Stopping Power, Lightweight, Hardline, Cold-Blooded, and Danger Close. Place your mouse over each icon to see the Pro version of it.

Stopping Power

The Stopping Power Perk
The Stopping Power perk increases bullet damage by 40%. When using a silenced sniper rifle, damage is less. Stopping Power negates the lesser damage of silencer.
Stopping Power Pro is acheived once the user gets 250 kills using the perk. Stopping Power Pro gives you increased damage against enemy vehicles.

Lightweight

The Lightweight Perk
The Lightweight perk allows the user to move faster by 7%. This perk is usually used by people who like to move fast with Marathon.
Lightweight Pro is unlocked after sprinting thirty miles. Lightweight Pro reduces the time from exiting sprint to being able to shoot.

Hardline

The Hardline Perk
The Hardline perk makes killstreaks one less kill. For example, if you want a UAV (3 kills), it will only take two kills with Hardline.
Hardline Pro is unlocked when the user gets fourty killstreaks (not 2 kills 40 times). Hardline Pro reduces the number of deaths for deathstreaks by one.

Cold-Blooded

The Cold-Blooded Perk
The Cold-Blooded perk removes their white hot body heat in thermal scopes. For killstreaks, the user is not seen as well. On a UAV, they will not be shown.
Cold-Blooded Pro is unlocked when the user destroys fourty enemy killstreaks with the perk. Cold-Blooded Pro removes enemy crosshairs and they will not see the red name over your head.

Danger Close

The Danger Close Perk
The Danger Close perk increases explosive weapon damage by 40%. It may come in handy with grenades or RPGs.
Danger Close Pro is unlocked when the user gets 100 explosive kills while using the perk. Danger Close Pro increases killstreak damage by 40% like Predator Missile and Copper Gunner.