Complete, mil-spec assembly with bolt, bolt carrier, and firing pin ready to drop into the rifle or carbine upper of your choice. Features a shot-peened bolt for increased surface strength and durability, and an extractor booster to ensure reliable cycling during rapid semi-auto or full-auto fire. Each assembly is magnetic particle inspection tested to ensure it's free from imperfections that can lead to premature failures. Properly staked gas key prevents gas leakage that can lead to short stroking. M16-style carrier on the black phosphate model has full-length shroud for tripping auto sear, so this carrier may be installed on full-auto law enforcement and military rifles. Mfg: Daniel Defense SPECS: Steel, black parkerized finish.