The POF-USA AR-15 Key Lock bolt carrier group is comprised of a Nitride heat treated carrier and stainless-steel gas key. The gas key fits into the dove tail at the front of the carrier and then secured by a staked screw. All AR-15 key Lock carriers come with a nickel-plated Mil-spec AR-15 Bolt assembly and the patented Roller Cam Pin. 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 steelThe Bolt is heat treated and shot peenedInstalled extractor includes black O-ring with springBolt Carrier is machined from 8620 steel and hardenedKey Lock Carriers are Nitride Heat TreatedRoller Cam Pin and Bolt Assembly are Nickel plated for corrosion resistance and smooth operationBolt Carrier will function in semi-auto AR-15 variantsGas Key Screw has been properly torqued and stakedNotched Gas Key for easy of roller cam pin re...