The MK18 AR15 style Upper Receiver Group is unmatched in size, weight, and performance, and features the picatinny quad rail Daniel Defense provides to USSOCOM. The RIS II rail features a Bolt-Up System that has been rigorously tested prior to fielding by USSOCOM. The 10.3 inch Cold Hammer Forged barrel is the same length in use for the MK18 upper most commonly used for CQB operations. Its independently ambi GRIP-N-RIP Charging Handle accommodates left- and right-handed shooters. All Daniel Defense complete upper receiver groups come standard with an M16 profile bolt carrier group.Once this part is assembled into a complete firearm, it becomes a regulated item by the National Firearms Act (NFA). Please check with your local and state municipalities for any further regulatory requirements. It is the buyer's responsibility to make sure they comply with all NFA rules and applicable laws.MATERIALS & CONSTRUCTION:UPPER RECEIVER: Mil-Spec with Indexing Marks and M4 Feed Ramps. CNC Machined of 7075-T6 Aluminum, Type III Hard Coat AnodizedBARREL: Chrome Moly Vanadium Steel, Cold Hammer Forged, 1:7 Twist, 10.3" Government Profile, Chrome Lined, Mil-Spec Heavy Phosphate Coated, and HP/MPI TestedGAS SYSTEM: Pinned Low Profile Gas Block CNC Machined of 4140 hardened steel with Mil-Spec Heavy Phosphate Coating, Carbine Length, Direct ImpingementMUZZLE DEVICE: Daniel Defense Flash Suppressor, 17-4 PH Stainless Steel, Salt Bath Nitride FinishedBOLT CARRIER GROUP: M16 Profile, Mil-Spec MP Tested, Chrome Lined, Properly Staked Gas KeySIGHTS: Sold SeparatelyHANDGUARD: Daniel Defense RIS II MK18, CNC Machined of 6061-T6 Aluminum, Type III Hard Coat AnodizedCHARGING HANDLE: GRIP-N-RIP Charging Handle, Body CNC Machined of 7076-T6 Aluminum, Handles & Latch CNC Machined of 6061-T6 Aluminum, Heavy Duty Stainless Steel Roll Pins, Type III Hard Coat AnodizedRAIL PANELS: Daniel Defense Rail Panels Made from Santoprene, Heat Resistant to 300Adeg F.Made in the USA!