The Palmetto State Armory Sabre Series Billet AR-15 Receiver Set is machined to have matching lines between uppers and lowers to give you a clean aggressive look while maintaining the tightest tolerances. CNC machined from 7075-T6 billet aluminum Mil-spec component compatible Ambidextrous bolt release (included) Integrated trigger guard Flared magwell Upper tensioning set screw Screw-in bolt catch pin Trigger reset set screw Threaded takedown spring hole Includes set screws 15.03 oz.