The Colt OEM Series offers a no-compromise solution for consumers and dealers to build and offer customized rifles based on the proven Colt M4 Platform. Handguards, Buttstock, Trigger Guard, Magazine, and Rear Sight have been omitted completely. The OEM1 is ready to accept most aftermarket Drop-In style Handguards that utilize the factory barrel nut and retaining ring. The OEM2 is build with a Low Profile Gas Block and without Handguard Retaining Ring to allow for the use of most aftermarket free float handguards. Specifications: Action: Semi-automatic Caliber: 5.56 NATO Barrel Length: 16.1" Finish Color: Matte Grips Stock: Pistol Grip Capac Mfg: Colt