If you are building an AR-15 stripped lower receiver into a complete rifle, you are going to need a lower parts kit. This AR-15 complete lower receiver parts kit includes, A2 pistol grip, pistol grip screw, pistol grip lock washer, disconnector spring, hammer pin and trigger pin, selector, selector spring, selector detent, magazine catch, magazine catch spring aluminum magazine catch button, bolt catch, bolt catch detent, bolt catch spring, bolt catch roll pin, take down pin, take down detent, take down detent spring, front pivot pin, front pivot pin detent, front pivot pin detent spring, aluminum trigger guard, trigger guard roll pin, buffer retainer detent, buffer retainer spring, trigger, trigger spring, hammer, hammer spring, disconnector. Made in the USA.