THIS KIT INCLUDES: Hammer Spring Disconnector Spring Trigger Pin x2 Trigger Spring Safety Selector Detent Ejector Spring Magazine Catch Spring Bolt Catch Spring Bolt Catch Plunger Bolt Catch Pin Takedown Spring Detent x2 Takedown Spring x2 Bua' er Retainer Bua' er Retainer Spring and Trigger Guard Pin. IMPORTANT: These components are built to Ruger fs standard of rugged reliability and are intended for use in AR-15 pattern firearms. However due to the wide variety of firearms and components available in the marketplace Ruger cannot guarantee that these components are compatible with all firearms. We cannot guarantee performance or fit and recommend installation by a qualified gunsmith to ensure maximum safety and performance.