Aero Precision APAR700315M48: This complete upper includes Aero Precision's 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. Aero Precision's 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. This complete upper does not include BCG or Charging Handle.Includes: M4E1 Threaded Assembled Upper Receiver 15" ATLAS S-ONE Handguard 20" 5.56 Rifle Length CMV Barrel Low Profile Gas Block and Rifle Length Gas Tube Product comes assembled