Radical Firearms RF-15, Semi-automatic, AR Pistol, 223 Remington/556NATO, 7.5 M4 Profile Threaded Barrel, Anodized Finish, Black, Pistol Length Gas System, A2 Flash Hider, MFT Engage V2 Grip, 7 M-LOK Handguard, 30 Rounds, 1 Magazine RF00133 The Radical Firearms 7.5" M4 Profile 5.56mm AR Pistol uses MIL-STD Upper and lower receivers along with their 7" RPR free float rail system for increased accuracy, keeping your hands cool, and giving you plenty of room for accessories.