The CMMG Gunbuilder Kit is a customizable lower parts kits for the AR-15 platform. This kit provides all the minor, mil-spec parts generally used in an AR-15 build, while still allowing the flexibilty to add common aftermarket upgrades, such as a pistol grip and match grade trigger components. Customizable lower parts kits offer an economical way to get all the small pieces needed for an AR-15 lower, without wasting money on the parts you won't use! Kit Includes Bolt Catch Bolt Catch Plunger Bolt Catch Roll Pin Bolt Catch Spring Buffer Retainer Buffer Retainer Spring Hammer Pin Magazine Catch Magazine Catch Button Magazine Catch Spring Pivot Pin Pivot Pin Detent Pivot Pin Detent Spring Selector Selector Detent Selector Detent Spring Takedown Pin Takedown Pin Detent Takedown Pin Detent Spring Trigger Pin Does NOT Include Pistol Grip Pistol Grip Screw and Washer Trigger or Hammer Trigger and Hammer Springs Disconnect Disconnect Spring Trigger Guard or Roll Pin