The Aero Precision XL Upper is forged from 7075-T6 aluminum and features an enlarged ejection port. The XL Upper Receiver is your best choice when you’re planning a build to send big rounds down range. Features- Port door opening enlarged to enhance larger diameter brass ejection laser marked “XL” designation on the upper receiver tang .250 takedown pin holes and laser engraved t-markings. Compatible with AR-15 Lower receivers AR-15 Port Doors and Forward Assists. Works with standard AR-15/M16 components. Includes port door and forward assist. NOTE: Requires charging barrel handguard gas block muzzle device gas tube and BCG (Bolt Carrier Group) to complete.