The CMMG AR-15 Lower Receiver Parts Kit includes all the parts you need to get started on your next AR-15 build. Combine this kit with a buttstock kit to complete your lower group. All parts meet or exceed Mil-Spec standard. Kit Includes Bolt Catch Bolt Catch Plunger Bolt Catch Spring Hammer Roll Pin Trigger Guard Trigger Guard Roll Pin Trigger Trigger Spring Trigger Pin Disconnector Disconnector Spring Hammer Hammer Spring Hammer Pin Safety Selector Mag Catch Mag Catch Spring Mag Release Button Detent Detent Spring Pivot Pin Safety Detent Safety Detent Spring Pistol Grip Pistol Grip Screw Buffer Retainer Buffer Retainer Spring Takedown Pin Detent Detent Spring