Manufacturer: Aero Precision Model: M4E1 Special Edition - Freedom Platform: AR-15 Receiver Type: Stripped lower receiver Caliber Compatibility: .223 Remington 5.56 NATO Other AR-15 calibers using standard AR-15 magazines and upper receivers Material: 7075-T6 forged aluminum Finish: Type III hardcoat anodized, black M4E1 Features Threaded bolt catch pin (eliminates roll pin installation) Integrated trigger guard Flared magazine well for faster reloads Reinforced receiver geometry with billet-style appearance Standard AR-15 fire control pocket Accepts mil-spec AR-15 lower parts kits (except for the threaded bolt catch hardware) Compatibility Compatible with most standard AR-15 upper receivers Accepts standard AR-15 buffer tubes and stocks Uses standard STANAG AR-15 magazines Works with standard AR-15 trigger groups Physical Specifications Material: 7075-T6 forged aluminum Color: Black Weight: Approximately 8.6 oz (244 g) Special Edition Features Patriotic "Freedom" roll mark with American flag engraving Limited production cosmetic variant of the standard M4E1 lower No functional differences from the standard M4E1 lower beyond the engraving Upgraded Freedom Barrel W American Flag & Eagle (1)30 RND MAG