KEY FEATURES Drop-On Upper Receiver Assembly that upgrades your AR15/M16/M4 type lower receivers or rifles 5.56 x 45mm NATO 16.25" Quick-Change Barrel 1:7" RHT, A 1/2"-28 TPI Short-Stroke Gas Piston Operation Dual-Feed(TM) - Accepts ALL AR15/M16 Magazines & M27 Linked Ammunition Precision Machined 7075-T6 Billet Upper Receiver, Feed Cover and Charging Handle Precision Machined Billet Steel Feed Tray Finish - Manganese Phosphate & Type III, Class 2 Hardcoat anodize - Black Full-Auto Bolt Carrier Handguard Style - MIL-STD 1913 Rail at 12 o'clock M-Lok at 3, 6 & 9 Adjustable Sight Set Quick-Change Barrel Handle Ships with Main Action Spring, Bolt Catch, Carbine Stock Spacer, (100) M27 Links & Operator's Manual Made In USA