Nickel Boron exterior gives this bolt an incredibly hard finish that protects against wear and corrosion for the ultimate in durability. The extreme smoothness and built-in lubricity of the coating also reduces friction and gives carbon deposits nowhere to stick, so bolt can be easily wiped clean with a cloth or nylon brush. Comes complete with ejector, extractor, and gas rings installed. Mfg: Wmd Guns SPECS: Carpenter 158 steel, NiB-X coating. Ejector, extractor, and gas rings included. Fits .223 5.56mm, 300 AAC Blackout, and similar AR platforms.