ZEROED Lower Parts Kit, AR15Finish your next AR15 lower receiver with the CMMG(R) ZEROED(TM) Mk4/AR15 lower parts kit. Every piece is made here in the USA and comes in convenient color-coded packets to make assembly a breeze. Check out our interactive install walkthrough video below or read the CMMG Resources LPK Install article for an in-depth breakdown. Don't forget a Buttstock or Brace kit to complete your pistol or rifle lower. All parts meet or exceed mil-spec. All installation hardware included.Kit Includes: ZEROED Extended Bolt Catch AR15 Bolt Catch Plunger, Spring, & Roll Pin ZEROED Trigger Guard, Screw, & Roll PIn Trigger & Trigger Spring Disconnector & Disconnector Spring Hammer & Hammer Spring Trigger/Hammer Retaining Pins ZEROED 60deg/90deg Adjustable Ambi Safety, Detent, & Spring ZEROED Ambi Magazine Catch & Spring ZEROED Extended Magazine Release Button HD Pivot/Takedown Pins, Detents, & Springs ZEROED Pistol Grip, Grip Screw, & Washer Buffer Retainer & Spring