AR15/M4 Mil-Spec Lower Parts Kit (Less Trigger)   1.   Grip   2.  Grip Screw Washer   3.   Grip Screw   4.   Bolt Catch   5.  Bolt Catch Plunger   6.  Bolt Catch Spring   7. Bolt Catch Roll Pin   8. Mag Release   9. Mag Release Button 10. Mag Release Spring 11. Buffer Retainer Spring 12. Safety 13. Buffer Retainer  14. Safety Detent Spring 15. Safety Detent  16. Trigger Guard  17.  Trigger Guard Roll Pin 18.  Takedown Detent Springs  19.  Takedown Detents  20.  Takedown Pins