Build and customize lower receivers using the Smith & Wesson M&P AR-15 Customizable Lower Parts Kit. Kit includes all the minor parts used in an AR-15 build, but allows the flexibility to add popular common aftermarket upgrades. The lower parts kit includes bolt catch, bolt-catch plunger, bolt-catch roll pin, bolt-catch spring, buffer retainer, buffer-retainer spring, hammer pin, magazine catch, magazine-catch button, magazine-catch spring, pivot pin, pivot-pin detent, pivot-pin detent spring, selector, selector detent, selector-detent spring, takedown pin, takedown-pin detent, takedown-pin detent spring and trigger pin. Made in USA.Manufacturer model #: 110115. Build and customize lower receivers Includes complete set of minor parts Allows popular aftermarket upgrades