Bling

Bling is a Tier 1 perk that appears in Call of Duty: Modern Warfare 2 and it will allow 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. The Bling perk icon is denoted with a shiny dollar sign.

This perk is unlocked at rank 21.

Limitations
There are some limitations as to which attachments can go together. You cannot combine the grenade launcher and shotgun attachments. You may only have one set of optics on the gun (Red Dot Sight, Holographic Sight, Thermal Scope, ACOG Scope, Sniper Scope, etc). The Suppressor attachment, Extended Magazines, and FMJ rounds can be used with any other attachment. If one has a Heartbeat Sensor equipped with a certain scope, the Heartbeat Sensor will be partially cut off from the screen. It is also advised not use this perk with newly acquired weapons, as they have no attachments unlocked.

Trivia

 * "Bling" is gangster-esque slang for jewelery.
 * In Call of Duty: World at War, you can find a Sawed-off Double-Barrel shotgun with a grip, much like Bling, as it has two attachments.
 * Bling is arguably most popular with Light Machine Guns in Modern Warfare 2 multiplayer due to it letting players use both a grip and another attachment, especially if they find the ironsights undesirable. Of course, this prevents you from using Sleight of Hand, which is sometimes necessary because of LMG's long reload times.