Upgrade your rifle with this 16 inch 5.56 NATO complete upper receiver. It includes a free-float 15 inch M-Lok handguard, nitride bolt carrier group (BCG), and a charging handle included. This upper is Mil-Spec compatible and ready to pair with any lower. Features 16 inch 5.56 NATO barrel with 1:7 twist, mid-length gas system, 1/2x28 muzzle threads, A2 muzzle device, and 15 inch handguard length. Includes steel barrel nut and screws. SPECIFICATIONS: Caliber 5.56mm NATO; Barrel Length 16 in.; Barrel Profile SOCOM; Muzzle Thread 1/2X28; Twist Rate 1:8; Gas System Mid-Length; Muzzle Device A2; Handguard Length 15 in.