This AR-15 lower receiver kit includes everything needed to build a complete lower receiver. Included is a bolt catch, plunger, roll pin, and catch spring; buffer retainer and spring; disconnecter and spring; hammer, pin and spring; magazine catch, button and spring; pistol grip, grip lock washer, and grip screw; pivot pin, pin detent, and pin detent spring; selector, detent and detent spring; takedown pin, pin detent, and pin detent spring; trigger, trigger guard, guard roll pin and a trigger pin/spring.