While progressing through the campaign of Call of Duty: Modern Warfare 3 players will have to scavenge for weapons and equipment in six of the fourteen missions. These Open Combat Area missions, as the game calls them, will drop players into an unmapped area and require the area to be searched for supply crates, armaments (known more commonly as killstreaks), and equipment like plate carrier upgrades. When players find the plate carrier upgrades they will expand their armor vest adding a plate slot.