The following perks can be unlocked.
Tier 1
Flak Jacket: Reduces explosive damage.
Flak Jacket Pro: Deflect fire damage, and safely toss back grenades.
Ghost: Undetectable by the Spy Plane and Blackbird.
Ghost Pro: Undetectable by aircraft, IR scopes, Sentry Guns, and no red cross hair on your name when targeted.
Hardline: Killstreaks require one less kill.
Harline Pro: Change the contents of a Care Package.
Lightweight: Move faster.
Lightweight Pro: No fall damage.
Scavenger: Get ammo from fallen enemies.
Scavenger Pro: Start with extra magazines, and get grenades from fallen enemies.
Tier 2
Hardened: Bullets penetrate better.
Hardened Pro: Increased bullet damage to killstreaks and less aiming recoil when shot.
Scout: Hold breath longer.
Scout Pro: Switch weapons faster.
Sleight Of Hand: Faster reloads.
Sleight Of Hand Pro: ADS with all weapons, except sniper rifles.
Steady Aim: Increased hip-fire accuracy.
Steady Aim Pro: Faster ADS after sprinting.
Warlord: Equip two attachments to your primary weapon.
Warlord Pro: Start with one extra lethal and tactical grenade (except Willy Pete).
Tier 3
Hacker: Ability to detect enemy equipment and explosives.
Hacker Pro: Booby trap enemy Care Packages and turn enemy killstreaks and equipment friendly.
Marathon: Longer sprint.
Marathon Pro: Unlimited duration.
Ninja: Silent movement.
Ninja Pro: Make no noise, and hear all enemies louder.
Second Chance: Ability to use your pistol before dying.
Second Chance Pro: Survive longer, and get revived by teammates.
Tactical Mask: Protects against Nova Gas.
Tactical Mask Pro: Reduces the effects of flash and concussion grenades.
