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