This CMMG Mk3 Enhanced Lower Receiver Parts Kit includes everything needed to build a complete a lower receiver, less a stock assembly and stripped lower receiver of your choice. Compatible with CMMG Mk3 Lowers and most LR308 type lowers. All parts are made to standard military specs. Kit Includes: Bolt Catch Bolt Catch Plunger Bolt Catch Roll Pin Bolt Catch Spring Buffer Retainer Buffer Retainer Spring Disconnector Disconnector Spring Hammer Hammer Pin Hammer Spring Magazine Catch Magazine Catch Button Magazine Catch Spring Pistol Grip Pistol Grip Lock Washer