The Aero Precision Field Repair Kit features many common parts for when your AR rifle breaks down. This kit includes: 2- AR15 Takedown Pin Detents, 2- Takedown Pin Springs, 2- Roll Pins Fwd Assist, 2- Bolt Catch Springs, Bolt Catch Buffer, 2- Bolt Catch Roll Pins, Trigger/Hammer Pin, Safety Selector Spring, Safety Selector Detent, Buffer Retainer, 2- Buffer Retainer Springs, 2- Trigger Guard Roll Pins, Pistol Grip Screw, Pistol Grip Lock Washer, Trigger Spring, Hammer Spring, Disconnector Spring, Nylon Tipped Tension Set Screw 1/4-28 x 1/2, 2- 4-40 Set Screw (for threaded takedown pin detent hole), and threaded Roll Pin and a M4E1 Lower Bolt Catch Pin. Get the best rifle repair kit today from LivenGood!