The Aero Precision AR-15 barreled upper receiver is built around the M4E1 Threaded upper receiver designed for use with standard barrel nuts. The receiver is forged from 7075-T6 aluminum and precision machined to M4E1 specs to ensure proper fit with Mil-Spec and aftermarket parts. It is matte black hardcoat anodized and features laser engraved T-marks on the upper picatinny rail. This 18” .223 Wylde barreled upper comes with the 15" Enhanced Keymod Gen2 free float handguard that features improved ergonomics, and a lightweight design with enlarged suppressor capable diameter.