Allows you to aim down the sight 50% faster than normal. Quickdraw is ideal for quick-scoping with Sniper Rifles.

Pro Ability: Allows you to recover from equipment and grenade usage faster.

Blast Shield / Blast Shield Pro

Greatly reduces explosive damage.

Pro Ability: Makes you immune to Stun and Flash Grenades.

Hardline / Hardline Pro

Reduces the amount of kills required for any killstreak by one. For example, the Care Package normally requires 4 kills, but with Hardline, you only need 3 kills. This perk returns in BO2, but will instead give you more points per action; check out the black ops 2 perks for other familiar MW3 counterparts.

Pro Ability: Two kill assists add one kill towards your next killstreak. Deathstreaks require one less death.

Assassin / Assassin Pro

Makes you undetectable by UAV, thermal scopes, Heartbeat Sensors and Portable Radars. You can still show up on the radar if you fire a weapon that doesn't have a silencer.

Assassin doesn't protect you from the Recon perk or the Recon Drone killstreak.

Pro Ability: Makes you immune to Counter-UAV and EMP. Enemies won't see a red crosshair or name when targeting you.

Overkill / Overkill Pro

Allows you to carry two primary weapons, but the second primary weapon can't be equipped with attachments.

Pro Ability: Your second primary weapon can now be equipped with attachments.