Aero Precision is an undeniable powerhouse in the AR-15 world, and that legacy continues with the new M4E1-T ATLAS R-One Complete Upper Receivers. Lightweight but rugged, Aero Precision's ATLAS attachment system is slim in the hand but maintains all the durability Aero Precision is known for. This upper comes assembled on an M4E1 threaded upper receiver with an 11.5" CMV 5.56 Barrel and includes a 9-inch ATLAS R-One M-LOK handguard. The new ATLAS R-One handguards are as function as they are aesthetic. These AR-15 handguards utilize 2 mirrored, tapered locking nuts that provide an evenly distributed clamping pressure across a custom barrel nut using a turnbuckle screw. QD sling cups are built into the side, providing an excellent base for a duty setup. With a carbine-length gas system and low-profile gas block, this upper receiver will function reliably even in difficult conditions. This upper receiver does not include a BCG or charging handle, which are necessary for function. Sights are not included, but a wide variety of sights and optics are available here at Primary Arms.Features: M4E1 Threaded Assembled Upper Receiver ATLAS R-ONE Handguard of choice 11.5" 5.56 CMV Barrel, Carbine Length Low Profile Gas Block and Carbine Length Gas Tube Product comes assembledAero Precision takes some of the most state-of-the-art manufacturing techniques and equipment derived from their work in the aerospace industry and applies it to their products in the firearms industry. They have utilized their knowledge from years of building aircraft components to design and engineer AR-15 handguards, receiver sets, scope mounts, and more. They treat every product as if it were a precision flying machine and adhere to strict quality standards to ensure law enforcement, military, and civilian customers receive a product they can rely on.