Aero Precision M5 Lower Parts Kit, For AR10, Includes Takedown/pivot Spring, Takedown/pivot detent, M5 .308 Takedown pin, M5 .308 Pivot pin, M5 .308 Bolt Catch, Bolt Catch Spring, Bolt Catch Buffer, Bolt Catch Roll pin, Safety Selector, Safety Selector Spring, Safety Selector Detent, Buffer Retainer, Buffer Retainer Spring, Magazine Catch Body, Magazine Catch Spring, and Extended Magazine Catch Button, Does not Include Fire Control Group or Pistol Grip APRH100386C Aero's M5 (.308) lower parts kit helps you to build a custom .308 AR from the ground up. Mil- spec dimensions and coating ensure the highest quality and correct component interface. This lower parts kit does not include the fire control group or pistol grip.