AR-15 LOWER PARTS BASIC BUILD KIT "Basic build" lower parts kit ready to complete your AR-15 lower receiver build. For use with the hammer and trigger of your choice (hammer and trigger not included). Includes Mil-spec magazine release, spring, and button Mil-spec hammer and trigger springs Mil-spec hammer and trigger pins Mil-spec bolt catch, spring, plunger, and roll pin Mil-spec buffer retainer and spring Mil-spec pivot pin, spring, and detent Mil-spec takedown pin, spring, and detent Mil-spec safety selector, spring, and detent Mil-spec disconnector spring Mfg: Kak Industry Llc.