The Luth-AR 11.5 Lightweight Complete Upper Barrel Assembly starts with our 11.5 5.56mm Lightweight barrel made from 4150 Chrome Molly with a 1-9 twist mated to our A3 Flattop receiver which includes our bolt carrier charging handle forward assist and ejection port cover. The upper is then topped off with our lo-profile gas system and our ergonomic 9 Palm Handguard� with KeyMod slots and a Picatinny top-rail. - 11.5 Lightweight Complete Upper Barrel Assembly - Includes: - HG-V-9K � Palm Handguard� � Vented 9 KeyMod with Barrel Nut - BL-L11 � 11.5 Lightweight Barrel - FTT-EA1 � A3 Upper Receiver Assembled - BC-A-223 � Fully Assembled Bolt Carrier � .223/5.56mm - BL-04A � Carbine Gas Tube - GB-LP750 � Gas Block .750 - UR-19 � Charging Handle - BL-06-A2 � A2 Flash Hider - Barrel Specs: - Lightweight 11.5 Barrel - 5.56 mm - 4150 Chrome Moly - Threaded Barrel � Thread Pitch 1/2 x 28 - Gas Block Diameter .750 - Gas Tube Length � Carbine - 1-9 RH Barrel Twist - 6 Lands and Groves - M4 Feed Ramp - Button Broached