TacFire Stripped AR-15 5.56x45mm NATO Upper Receiver Black Anodized. The only thing you need to finish your upper is a BCG barrel gas block gas tube handguard and muzzle device. (sold separately) Specifications for TacFire Stripped AR-15 5.56x45mm NATO Upper Receiver: Manufacturer: TacFire Color: Black Finish: Anodized Caliber: 5.56x45mm NATO Gun Make: AR Platform Gun Model: AR-15 Condition: New Country of Origin: USA Package Contents: TacFire Stripped AR-15 5.56x45mm NATO Upper Receiver What firearm models does the manufacturer say TacFire Stripped AR-15 5.56x45mm NATO Upper Receiver is compatible with? The manufacturer says that TacFire Stripped AR-15 5.56x45mm NATO Upper Receiver is compatible with AR-15TacFire UP01C2: Stripped AR-15 5.56x45mm NATO Upper Receiver Black Anodized