Tiger Rock Threaded Barrel 5.56 NATO 16in Mid Length. 1-7 Twist 1/2x28 Thread Pitch Parkerized Finish Black Large. Specifications for Tiger Rock 5.56 NATO Threaded Barrel: Manufacturer: Tiger Rock Fabric/Material: 4150 Heat Treated Chrome Moly Steel Caliber: 5.56x45mm NATO Threads per Inch: 1/2x28 Features of Tiger Rock 5.56 NATO Threaded Barrel Fits: AR-15 Package Contents: Tiger Rock 5.56 NATO Threaded Barrel What firearm models does the manufacturer say Tiger Rock 5.56 NATO Threaded Barrel is compatible with? The manufacturer says that Tiger Rock 5.56 NATO Threaded Barrel is compatible with AR-15Tiger Rock BR167-P: Threaded Barrel 5.56 NATO 16in Mid Length. 1-7 Twist 1/2x28 Thread Pitch Parkerized Finish Black Large