This high quality bolt carrier group is a valuable addition to your AR15 build. Features: M16-cut carrier Machined from 8620 Tool Steel (Carrier) and 9310 Steel (Bolt) Carrier has forward assist serrations Black Nitride Finish - advanced lower friction coating that minimizes the need for lubricants and cleaning Properly staked gas key Shot peened HPT tested/MPI marked Black o-ring insert on extractor High quality BCG