Metal Gear Solid 4 uses a split inventory system where the player character, Old Snake, can equip up to five weapons, which are then available using a quick-access menu; this is explained as Snake's "backpack," despite that he is not actually wearing one. The rest can be accessed via the pause menu, this swapping explained in-game as the TARDIS-like depths of Metal Gear Mark 2, a foot-tall robot which seemingly has no issues containing more or less every weapon on this page along with enough ammunition to destroy Belgium. Snake's currently equipped weapons each count their weight towards a total for all gear; heavy loads will cause his "stress" meter (which governs how well he can aim ranged weapons) to rise faster when he moves around. Only weapons count towards weight; ammunition is treated as weighing nothing. This gets bizarre with disposable systems where each reload is a whole weapon in itself but all except the currently held one are treated as weightless "ammunition;" for example, only one of the fifty LAWs Snake can be carrying actually weighs anything for purposes of inventory weight.