Three Tiers of perks with a total of sixteen options are found in Modern Warfare 2. These are Passive rewards that help benefit the player and the play still that is needed to help dominate the game. Each Perk has a Pro option that can be unlocked after completing some challenges.
Perk Tier 1
Pro: Climb obstacles faster.
Slight of Hand
Pro: Faster Aiming.
Resupply from dead enemies.
Pro: Extra Mags.
Unlocked: Level 13
2 primary weapons.
Pro: 2 secondary weapon attachments.
Unlocked: Level 21
One Man Army
Swap classes at any time.
Pro: Swap classes faster.
Unlocked: Level 45
Perk Tier 2
Increased bullet damage.
Pro: Extra damage vs. enemy vehicles.
Pro: Quick aim after sprinting.
Killstreaks require 1 less kill.
Pro: Deathstreaks require 1 less death.
Unlocked: Level 9
Undetectable by UAV, air support, sentries, and thermal.
Pro: No red crosshair or name when targeted.
Unlocked: Level 25
Increased explosive weapon damage.
Pro: Extra air support damage.
Unlocked: Level 33
Perk Tier 3
Increased melee distance.
Pro: No falling damage.
Increased hip fire accuracy.
Pro: Longer hold breath duration.
Jam enemy radar near you.
Pro: Delay enemy Claymore explosions.
Unlocked: Level 17
Invisible to heartbeat sensors.
Pro: Your footsteps are silent.
Unlocked: Level 29
Detect enemy explosives and tactical insertions.
Pro: Louder enemy footsteps.
Unlocked: Level 37
Pull out your pistol before dying.
Pro: Use equipment in last stand.
Unlocked: Level 41