Modular buttstock assembly for the AR Interchangeable with standard A1 or A2 buttstocks or any aftermarket buttstock with overall length of approximately 10.5. Fully Ambidextrous and can be comfortably used shooting off either shoulder (Cheek piece pre-installed for right-handed shooters but can be installed on either side for right- or left-hand shooters). Cheek piece not only moves up and down, it also moves back and forth on the stock. *NOT interchangeable with carbine/collapsable rifles with telescoping assemblies (6-position tubes). You will need to purchase a MBA-3 or MBA-4 to fit these carbine tubes