Spike’s Standard Lower Parts Kit exceeds military specifications by a long shot while also offering a much better fit and finish. It includes: rounded hammer (works with all calibers) hammer spring trigger trigger spring disconnector disconnector spring safety selector detent selector spring bolt catch bolt spring roll pin plunger magazine catch catch spring catch button front pivot pin rear takedown pin aluminum trigger guard with spring loaded detent and roll pin buffer retainer spring and plunger A2 Pistol grip 1/4×28″ hex screw star lock washer and stainless steel hammer and trigger pin with black oxide finish. Made in the USA.