The AR-STONER(TM) Extreme Duty Upper Receiver is a great choice for your next custom AR-15 build. The AR-STONER(TM) upper receiver is ready to be installed onto any standard AR-15 lower. The receiver is forged from aluminum to military specifications and then Type III hard coat anodized. Whether at the range or in the field, the high quality AR-STONER(TM) upper receiver performs to perfection! FeaturesDry Film LubedM4 Feed Ramps