The POF-USA nickel plated AR15 bolt assembly is manufactured to MIL-SPEC and is ready for any AR-15/M16 carrier. In addition to being compatible with both piston and DI rifles, it comes with the extractor and ejector installed. FeaturesMagnetic Particle Inspected (MPI)Machined from 9310 steelHeat treated and shot peenedInstalled Extractor includes black o-ring with springNickel PlatedFor 5.56 NATO/.223 REM or 300 Blackout AR-15/M16 variants