Jacob Grey Firearms AR-15 Threaded Barrel AR 9mm 4.5in 1-10 Twist 1/2x36 Thread Black. Pairs perfectly with JG low profile handguard. Specifications for Jacob Grey Firearms AR-15 Threaded Barrel: Manufacturer: Jacob Grey Firearms Color: Black Finish: Nitride Caliber: 9mm Luger Barrel Profile: Light Gas Block Journal Size-Diameter: .750 in Threads per Inch: 1/2x36 Barrel Twist Rate: 1-10 Barrel Material: 4150 Chrome Moly Vanadium Flutes: No Gun Make: AR Platform Gun Model: AR-15 Package Contents: Jacob Grey Firearms AR-15 Threaded Barrel What firearm models does the manufacturer say Jacob Grey Firearms AR-15 Threaded Barrel is compatible with? The manufacturer says that Jacob Grey Firearms AR-15 Threaded Barrel is compatible with AR-15Jacob Grey Firearms 9MM45B36: AR-15 Threaded Barrel AR 9mm 4.5in 1-10 Twist 1/2x36 Thread Black