CMMG Lower Parts Gunbuilder's Kits contain the needed parts to complete an AR-15 lower receiver. These kits come less the trigger, grip and trigger guard.Kit Includes: Takedown pin Receiver pivot pin Takedown pin detent (2) Takedown pin detent spring (2) Hammer and trigger pin (2) Safety selector Selector detent Magazine catch Magazine catch spring Magazine release button Bolt catch Bolt catch plunger Bolt catch spring Bolt catch spring pin Buffer retainer and buffer retainer spring.