Light weight stock to mount to a carbine rifle (6-positions mil-spec or commercial tube). This is our carbine skullaton stock – Fits all .223 and most .308 AR carbine style rifles – Super Strong Glass Filled Nylon – 21st century look – Ergonomic – Easy to replace and quick to install – Uses 4 out of the 6 positions on a mil-spec or commercial tube – Features – Available in Black or Flat Dark Earth – Lightweight buttstock for the carbine AR weighing in at 9.5 ounces – Picatinny Rail – Revolutionary Anti-Rattle Set Screw – Easy to add our Cheek Piece: Cheek piece will add an additional 1 height on cheek rest – Easy to add our Butt Plate Assembly or 3-Axis Butt Plate Assembly: The assemblies will add an additional 1 1/16 length of pull with extended length buttplate – Adapts To Existing Commercial and Mil-Spec Buffer Tubes – Certain after Market Commercial Buffer Tubes that exceed 1.1172 diameter may not fit – Caution: the MBA-3 and MBA-4 Carbine buttstocks are not designed to be used with Large Bore Calibers such as .338 Lapua or .50 BMG applications. See our MBA-1 and MBA-2 Rifle buttstocks as alternatives – The MBA-4 Carbine buttstock is NOT interchangeable with A2 standard buffer tube. You will need to purchase a MBA-1 or MBA-2 Rifle buttstock to fit A2 tubes