Description This complete upper includes our new ATLAS S-ONE Handguard! The S-ONE line of handguards are designed with size and weight in mind, providing the perfect addition to your lightweight build. Our proprietary ATLAS attachment system is a durable and dependable mounting platform, maintaining a slim profile while still providing the strength and stability customers have grown to love from Aero Precision handguards. Includes: M4E1 Threaded Assembled Upper Receiver 9" ATLAS S-ONE M-LOK Handguard 11.5" 5.56 CMV Barrel, Carbine Length Low Profile Gas Block and Carbine Length Gas Tube Product comes assembled This complete upper does not include BCG or Charging Handle. These products may be selected as add-ons under the Finish Your Build tab The muzzle brake that comes with this complete upper receiver is NOT pinned nor welded to this barrel.