Rock River Arms Completed Upper Receiver A4 9MM Luger 10.5 Inch Barrel 1-10 Twist 1/2-36 Thread R4 Handguard A2 Flash Hider Black. . Formulated working with several of the very most robust and dependable materials available these AR15 Upper Receivers from Rock River Arms can provide a product that will give many years of dependability. Rock River Arms has been making high-quality merchandise for a number of years and the Rock River Arms A4 9MM Luger Completed Upper is their very own manner of showing you exactly how much they are concerned. Here at OpticsPlanet we make it our responsibility to get the perfect product for all your preferences and exhibiting the Rock River Arms A4 9MM Luger Completed Upper is something that we are pleased to offer. Specifications for Rock River Arms A4 9MM Luger Completed Upper: Manufacturer: Rock River Arms Caliber: 9mm Luger Barrel Twist Rate: 1-10 Threads per Inch: 1/2x36 Handguard Type: R4 Finish: Anadized Color: Black Fabric/Material: Aluminum Barrel Material: Chrome Moly Bolt Carrier Group Included: COM-SPEC Magazine Included: No Package Contents: Rock River Arms A4 9MM Luger Completed Upper Bolt Carrier Group Charging Handle Assembly Rock River Arms 9MM0364B: Completed Upper Receiver A4 9MM Luger 10.5 Inch Barrel 1-10 Twist 1/2-36 Thread R4 Handguard A2 Flash Hider Black