The POF-USA Milspec Enhanced Bolt Carrier Group is great for those shooters who want more than a standard Mil-Spec carrier. The carrier and bolt are nitride heat treated with a hard chrome firing pin. With the addition of the Roller cam pin, your rifle will never suffer premature cam slot wear. FeaturesFully assembled Bolt Carrier Group; including the bolt, bolt carrier, gas key, firing pin, roller cam pin, and firing pin retaining pinEvery Bolt is Magnetic Particle Inspected (MPI)The Bolt is machined from 9310 steelFollowing machining, the Bolt is heat treated and shot peenedInstalled extractor includes black O-ring with springBolt Carrier is machined from 8620 steel and hardened.Bolt Carrier Key, Bolt Carrier, and Bolt Assembly are Nitride Heat TreatedBolt Carrier will function in semi-auto or full-auto AR-15/M16 variantsGas Key Screws are properly torqued and stakedNotched Gas Key for easy of roller cam pin removalFull-auto Tail Length