There are many modifications that are available for all marker models in paintball.  Many of these modifications will improve the performance of your gun, while some are simply for cosmetic purposes.  There are some pieces for guns however that play the role of both.  One of these in particular are buttstocks.  There are many reasons why players equip their markers with buttstocks.  The primary reason is functional; these parts can definitely help bring more balance to the weight of the gun, not to mention significantly increasing accuracy by offering a place to stabilize against your shoulder or cheek while shooting.