This high quality bolt carrier group is a valuable addition to your AR15 build.Features:M16-cut carrierMachined from 8620 steelCarrier has forward assist serrationsMil-Spec phosphate coatingProperly staked gas keyChrome lined gas key and bolt channel5.56 Bolt is machined from Carpenter 158 tool steelShot peenedHPT tested/MPI markedBlack o-ring insert on extractorHigh quality BCG