This assembled upper includes Aero Precision's new ATLAS R-ONE Handguard! The R-ONE handguards are designed with size and weight in mind, while still providing plenty of real-estate to accommodate any attachment needs the end user may have. Their 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 - Anodized Black or Cerakote FDE depending on model. 15" ATLAS R-ONE M-LOK Handguard with 16"CMV Barrel OR 15" ATLAS R-ONE M-LOK Handgua Mfg: Aero Precision