Aero Precision AR15 Complete Upper, 223 Remington/556NATO, 20 Barrel, 1:7 Twist, A2 Detachable Carry Handle and A2 Front Sight Block, Rifle Length Gas System, Anodized Finish, Black, Does Not Include BCG or Charging Handle APAR505611 This AR15 Complete Upper is the same upper receiver used in the AERO M16A4 Special Edition Complete Rifle and features a 20" 5.56 Barrel with Pinned FSB" A2 Handguard and A2 Detachable Carry Handle.