Aero Precision Fix it Kit - Includes Takedown Pin Detent (4) - Takedown Pin Spring (4) - Bolt Catch Roll Pin (2) - Trigger/Hammer Pin (2) - Safety Selector Spring (2) - Safety Selector Detent (2) - Buffer Retainer (2) - Buffer Retainer Spring (2) - Disconnector Spring (2) - and 4-40 Set Screw (for Threaded Takedown Pin Detent Hole) (2) APRH101627