Brownells has paired up the Daniel Defense M4A1 FSP AR15 style Upper Receiver Group with your choice of EOTech Red Dot EXPS2-0 or EXPS3-0. This Daniel Defense M4A1 FSP AR15 style Upper Receiver Group was built for customers wanting a firearm inspired by USSOCOM SOPMOD Block II. It features the M4A1 FSP RIS II picatinny quad rail in Flat Dark Earth, a 14.5" M4 SOCOM heavy profile barrel, Mil-Spec F-Marked front sight base. UPPER RECEIVER: Mil-Spec with Indexing Marks and M4 Feed Ramps. CNC Machined of 7075-T6 Aluminum, Type III Hard Coat Anodized BARREL: Chrome Moly Vanadium Steel, Cold Hammer Forged, 1:7 Twist, 14.5" M4 SOCOM Heavy Profile, Chrome Lined, Mil-Spec Mfg: Brownells Bundles