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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

I like how they make it more challenging to get pro perks and how they have the description for SOH Pro ADS with all weapons, except sniper rifles lulz

they think they can stop quickscoping just cuz they took it off for snipers. >.< i don't think so