TacFire Bu-556-16 Rifle Upper Assembly 5.56 Nato Caliber With 16" Black Nitride Barrel, Black Anodized 7075-T6 Aluminum Receiver & M-LOK Handguard For AR-Platform Includes Bolt Carrier Group Chambered In 5.56, This Rifle Upper Is Completely Built And Ready To Be Put On a Lower. Includes a Bolt Carrier Group. Type: Complete Caliber: 5.56X45mm Nato Sights: None, Optic Ready Barrel Length: 16" Barrel Finish: Black Nitride Receiver Finish: Black Anodized Handguards: M-LOK Handguard Finish: Black Barrel Length Range: 16" To 16.99"