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