Product Features & Specifications Colt Mfg CR6920MPSFDE M4 Carbine 5.56x45mm NATO 30+1 16.10", Black Rec, FDE Magpul Furniture, SL Carbine Stock & Grip, Vertical Grip, MBUS Rear Sight This Semi-Automatic Colt Carbine is the standard by which all Modern Sporting Rifles and Law Enforcement Carbines are judged. It features a fixed A2 front sight and Magpul MBUS rear sight, a barrel with grenade launcher cutout, dual heatshield handguards, flat top upper receiver, and buttstock which define this modern classic. Colt CR6920 M4 Carbine 223 Rem/5.56 NATO Rifle