AR15/M4 Mil-Spec Lower Parts Kit (Less Trigger, Less Grip)   1.  Bolt Catch   2.   Bolt Catch Plunger   3.   Bolt Catch Spring   4.  Bolt Catch Roll Pin   5.  Mag Release   6. Mag Release Button   7. Mag Release Spring   8. Buffer Retainer Spring   9. Safety 10. Buffer Retainer  11. Safety Detent Spring 12. Safety Detent  13. Trigger Guard  14. Trigger Guard Roll Pin 15. Takedown Detent Springs  16.  Takedown Detents  17.  Takedown Pins