Franklin Armory Libertas Proprietary Billet Lower Receiver, Machined From 7075-T6 Aluminum, Hard Coat Type III Anodized Black, Flared Magazine Well for Quick Magazine Changes, Ambidextrous Push Button QD Sling Mounts, Integral Cold Weather Trigger Guard, Serrated Memory Index Point for Shooting Finger, Textured Front Area for Offhand Grip, Specialized Tension Screw - Eliminates Upper/Lower Play, Franklin Armory Binary Firing System, Ergo Ambi Sure Grip, Magazine Magpul Pmag P30, Stock B5 SOPMOD Stock, Six Position Receiver Extension Installed, MILSPEC Diameter