If you do not plan to sell the modkit, or don't have the weapon, don't bother picking them up. These modifications are only for only one weapon and one weapon only. Restricted weapon mods take up 2x1 inventory space. Unlike general modifications, these appear as red boxes (but take up less space in the inventory). Some weapons can use them, others cannot. These modifications are only for certain weapons. All general weapon mods take up 2x2 inventory space. Potential growth in an area is represented by a grayed-out 'bars' in the stat. You can install as many general weapon mods as a weapon can allow, so long as it has potential to grow in one of the four statistics: Rate of Fire, Reload Speed, Damage Increase, and Ammo Increase.
