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