The Radical Firearms M4 Profile 5.56mm AR Pistol uses MIL-STD Upper and lower receivers along with the RPR free float rail system for increased accuracy, keeping your hands cool, and giving you plenty of room for accessories. Regardless if it's your first or fiftieth, a Radical Firearms AR pistol will not disappoint! FeaturesM-Lok HandguardM4 Feed Ramps0.750 Low Profile Gas BlockA2 Flash HiderMIL-STD Fire Control Group