Sons of Liberty Gun Works M4-EXO3 AR-15 11.5 inch .223 Wylde Upper Receiver Group Medium Carbine 1-7 A2 Black. These uppers are assembled with our V2 gas blocks made from 4140 steel for a solid efficient gas seal. Specifications for Sons of Liberty Gun Works M4-EXO3 AR-15 11.5 inch .223 Wylde Upper Receiver Group: Manufacturer: Sons of Liberty Gun Works Caliber: .223 Wylde Barrel Length: 11.5 in Barrel Profile: Medium Gas System Length: Carbine Length Barrel Twist Rate: 1-7 Muzzle Device: A2 Flash Hider Finish: Anodized Color: Black Fabric/Material: 416 Stainless Steel Handguard Length: 10.75 in Gun Make: AR Platform Gun Model: AR-15 Bolt Carrier Group Included: No Charging Handle Included: No Package Contents: Sons of Liberty Gun Works M4-EXO3 AR-15 11.5 inch .223 Wylde Upper Receiver Group What firearm models does the manufacturer say Sons of Liberty Gun Works M4-EXO3 AR-15 11.5 inch .223 Wylde Upper Receiver Group is compatible with? The manufacturer suggests that Sons of Liberty Gun Works M4-EXO3 AR-15 11.5 inch .223 Wylde Upper Receiver Group is compatible with AR-15Sons of Liberty Gun Works U-M4EXO3-556-115-A2: M4-EXO3 AR-15 11.5 inch .223 Wylde Upper Receiver Group Medium Carbine 1-7 A2 Black