Stickers, which can be added to weapons on a loadout card or basic card even for no cost.
Stickers must be obtained individually to be attached.
*removing sticker costs 250 credit
Stickers are not returned when you trade up.
Stickers don’t come in any of the loadout card by default.
Attachment ideas,
Allows zoom, increased accuracy, decreased mobility
Red Dot Sight
ACOG sight
Holographic Sight
X6 Sniper rifle scope
Laser (increased accuracy, laser is visible)
Recoil pad (Reduced recoil, decreased mobility)
Extended mag (+35% ammo, decreased mobility)
Grip (reduced recoil, slower aim speed)
Rapid Fire (smg only) Increased fire rate, reduced accuracy
Silencer (reduced recoil, reduced sound, reduced damage)
Barrel extension (Increased all accuracy, decreased mobility)
Shorter Barrel (increased mobility, Reduced hip fire accuracy.)
Bayonet (quicker melee)
and more that I can’t think up on the spot. 
