The Radical Firearms 10.5" M4 Profile 5.56mm AR Pistol uses MIL-STD Upper and lower receivers along with our 10" RPR free float rail system for increased accuracy, keeping your hands cool, and giving you plenty of room for accessories. Starting in 2019 we are excited to be add the SB-Tactical SBA3 5 postion adjustable pistol brace line of pistols. Regardless if it’s your first or fiftieth, a Radical Firearms AR pistol will not disappoint!