CMC Triggers Complete lower receiver parts kit for AR-15 are a great addition to your AR15 build. From amateur gun builder to seasoned expert gun smith, this lower parts kit is for you. Kit contains the following:-Bolt Catch, Bolt Catch Plunger, Bolt Catch Spring, Bolt Catch Roll, Mag Release and Mag Release Button, Mag Release Spring, Buffer Retainer Spring, Safety, Buffer Retainer, Safety Detent Spring and Safety Detent, Trigger Guard and Trigger Guard Roll Pin, Takedown Detent Springs and Takedown Detents and Takedown Pins. All parts meet or exceed MIL SPEC. NOTE: Fire control group and grip NOT included.