Bling

Bling is a Tier 1 perk that appears in Call of Duty: Modern Warfare 2. It allows players to put two attachments onto their primary weapon. The pro version of the perk also allows the player to put 2 attachments on their secondary weapon as well as their primary. The Bling perk icon is denoted with a shiny dollar sign. Bling is unlocked at level 21.

Benefits
The primary benefit of Bling is synergy: Bling allows players to create a combination of weapon attachments that is more effective than the sum of its parts. Examples include:
 * The FAL: This weapon's iron sights are extraordinarily restrictive; additionally, the Holographic Sight provides the FAL with a small damage boost at long range. Bling allows players to deploy a FAL with both a Holographic Sight and another attachment.
 * The Model 1887: Though the effectiveness of Akimbo Model 1887s was reduced in 1.07, Bling Pro allows players to use these shotguns much as they did before the patch by equipping the FMJ weapon attachment as well as Akimbo.
 * The Shotgun (attachment): Since some players rely on shotgun secondary weapons for close range combat, adding an underbarrel shotgun to any assault rifle allows players access to a shotgun while simultaneously freeing up their secondary weapon slot for weapons such as launchers or pistols. Bling allows players to both deploy an underbarrel shotgun and equip their assault rifle with a sight or silencer.
 * The M16, FAMAS, or M93 Raffica: All of these weapons fire in three-shot bursts. Even when suppressed, these weapons can usually take down a target within 3-6 hits, which both saves ammunition (mitigating the impact of the lack of the Scavenger perk) and provides incentive for players to field suppressed versions of these weapons. Bling allows players to deploy both a sight of their choice as well as a silencer.
 * Some snipers find the combination of Thermal Scope and silencer to be advantageous.
 * Another common combination of attachments is the Suppressor and either the Red Dot Sight or Holographic Sight. This is because it allows easy aiming while staying off the radar.

Limitations
Bling has several limitations. Since it takes up a tier-1 perk slot, it has the effect of limiting a player's mobility by preventing them from taking the Marathon perk, as well as limiting a player's ability to resupply in the field by preventing them from taking Scavenger or One Man Army (the latter weakness can be overcome somewhat by utilizing a Throwing Knife as a source of renewable ranged kills). Additionally, there are some limitations as to which attachments can go together. Players cannot combine attachments which take up the same place on the gun, such as the Grenade Launcher and the Masterkey Shotgun because both are under-barrel mounted. Players also can only have one set of optic sights or Akimbo equipped on a gun (Red Dot Sight, Holographic Sight, Thermal Scope, ACOG Scope, Sniper Scope). The Grip, Rapid Fire, Suppressor, Heartbeat Sensor, Extended Magazines, and FMJ rounds can be used with any other attachment.

Trivia

 * Bling is most popular with Light Machine Guns as they have large ammo reserves which negate the need for Scavenger and many players feel that the Grip attachment is a requirement.
 * Using FMJ rounds with optics (on Assault Rifles and SMGs especially) can be very helpful for unlocking Extended Mags.
 * When prompted to pick up a weapon, it will only show it's a bling weapon, eg. FAMAS Bling. Thus, you can pick up a gun with attachments you may hate, as it doesn't show the available attachments, like FAMAS Red Dot Sight.