This complete upper includes our new ATLAS S-ONE Handguard! The S-ONE line of handguards are designed with size and weight in mind, providing the perfect addition to your lightweight build. Our proprietary ATLAS attachment system is a durable and dependable mounting platform, maintaining a slim profile while still providing the strength and stability customers have grown to love from Aero Precision handguards.Includes: M4E1 Threaded Assembled Upper Receiver ATLAS S-ONE Handguard of choice 16" .223 Wylde Mid-Length Fluted Stainless Steel Barrel Low Profile Gas Block and Mid-Length Gas Tube Product comes assembled This complete upper does not include BCG or Charging Handle.M4E1 Threaded Upper Receiver Features: New enhanced forging that gives the upper receiver a "billet look" New picatinny profile that blends seamlessly with our Enhanced Series Handguards M4 Feedramps .250 takedown pin holes Laser engraved T-marks Includes port door and forward assist installedATLAS S-ONE Handguard Features: Front and rear picatinny rail Eliminated center of top rail for weight reduction Indexing grooves in 12:00 position for positive grip control Quick disconnect sling socket at the 3, 6 and 9 o'clock positions Compatible with low profile gas blocks 1.3" Inside diameter 1.5" Outside diameter Compatible with mil-spec AR-15 upper receivers and barrels16" .223 Stainless Steel Mid-Length Barrel Features: .223 Wylde 16" Fluted Mid-Length Barrel, 1/8 Twist 416R Stainless Steel Bead Blasted Finish .750 gas block journal Mid-length gas system M4 Feed Ramp Extension HP and MPI tested Standard A2 flash hiderThis barrel features some of the most aggressive and weight reducing flutes on the market. Coming in at a total weight of 27 oz. We've managed to cut almost a pound out of the barrel all while not sacrificing one ounce of accuracy!SpecsShipping to FFL Dealer RequiredNoMade In AmericaYesPlatformAR-15SeriesATLASCaliber.223 WyldeBarrel Length16"Select Your FinishNoWeight(s)52.6 ozOtherNOTE: Weights above include Gen 2 Upper, Handguard, Barrel, Muzzle Brake and Mounting Hardware.