Brownells has taken the guesswork out for you! Need a lower parts kit? We have put together the small parts needed from some of our top suppliers just for you! This kit includes the following items: Magazine Release Magazine Release Button Magazine Catch Spring Bolt Catch CMMG Trigger Hammer Assembly Hammer Spring Trigger Disconnector Spring Trigger Spring Disconnect Disconnect Spring Safety Selector Selector Spring Selector Detent Pistol Grip Screw Pistol Grip Washer A2 Pistol Grip Takedown/Pivot Pins Mfg: Brownells