Aero Precision APAR501801A Complete Stripped Upper Multi-Caliber Brl Finish The AR15 Assembled Upper Receiver comes with the port door and forward assist already installed. Forged from 7075-T6 aluminum, this assembled upper is precision machined to mil- spec M16/M4 specifications and features M4 feedramps. It includes M4 Feedramps and .250 takedown pin holes. This assembled upper receiver is finished in FDE Cerakote. Type: Stripped Caliber: Multi-Caliber Sights: None, Optic Ready Barrel Length: N/A Receiver Description: 7075-T6 Aluminum M4 Receiver Finish: FDE Cerakote