This Daniel Defense M4A1 FSP AR15 style Upper Receiver Group was built for customers wanting a firearm inspired by USSOCOM SOPMOD Block II. This upper features the M4A1 FSP RIS II picatinny quad rail in Flat Dark Earth, a 14.5" M4 profile barrel, Mil-Spec F-Marked front sight base, Surefire SF3P flash hider / suppressor adapter, A1.5 Fixed Rear Sight, M16 profile full auto bolt carrier group, and Rail Mounted QD Swivel Attachment Point with QD swivel.Features :UPPER RECEIVER: Mil-Spec with Indexing Marks and M4 Feed Ramps. CNC Machined of 7075-T6 Aluminum,BARREL: Chrome Moly Vanadium Steel, Cold Hammer Forged, 1:7 Twist, 14.5" M4 Profile, Chrome Lined, Mil-Spec Phosphate Coated,GAS SYSTEM: Mil-Spec F-Marked Front Sight Base, Carbine Length, Direct ImpingementMUZZLE DEVICE: Surefire SF3P Flash Hider / Suppressor Adapter, Black Ionbond DLC Coating, Pinned and Welded to BarrelBOLT CARRIER GROUP: M16 Profile, Mil-Spec MP Tested, Chrome Lined, Properly Staked Gas KeySIGHTS: A1.5 Fixed Rear Sight, 6061-T6 Aluminum, Type III Hard Coat AnodizedHANDGUARD: Daniel Defense M4A1 FSP Rail Interface System (RIS) II, CNC Machined of 6061-T6 Aluminum, Type III Hard Coat Anodized FDE