This Bolt Carrier Group (BCG) comes fully assembled and ready to drop into most mil spec AR10 upper receivers. All critical parts are coated with EXO Nickel Boron technology that provides permanent dry lubricity, extreme durability and increases both wear and corrosion resistance. Our patented Nickel Boron coating will reduce friction and improve the overall performance of your rifle. Warranty Note: "The carrier comes with a black topcoat/exterior with FailZero EXO Nickel Boron underneath. We've introduced this carrier to provide non-reflective properties, resulting in a Tactical Advantage. However, PLEASE NOTE that wear areas including ramps, rails, and other contact points such as carrier ends will wear - exposing the Nickel Boron coating beneath. The critical non-wear areas which are exposed during operation, i.e. the dust cover area will remain black. Typically non-wear areas on outside of the carrier will retain the black overcoat." Note: DPMS Pattern Nickel Boron treated parts include: Bolt & Extractor (.308 compatible) Bolt Carrier Extractor Cam Pin Carrier Key Firing Pin