CMC Triggers Complete Lower Receiver Parts Kit for AR-15 is a great addition to your AR15 build. From amateur gun builder to seasoned expert gun smith, this lower parts kit is for you. Included: Bolt CatchBolt Catch PlungerBolt Catch SpringBolt Catch Roll PinMag ReleaseMag Release ButtonMag Release SpringBuffer Retainer SpringSafetyBuffer RetainerSafety Detent SpringSafety DetentTrigger GuardTrigger Guard Roll PinTake-down Detent SpringsTake-down DetentTake-down Pins#html-body