RISE Armament’s AR-15 Lower Parts Kit is a must have for anyone building a custom AR platform, or who want to optimize an existing AR. The majority of the parts in this kit are made from industry-standard 8620 steel – a full-up alloy of nickel, chromium, molybdenum, with 0.2 percent carbon. This gives these parts incredible strength and durability for a lifetime of reliable service. The parts are also given a black phosphate finish, which deposits an inert layer on top of the steel to prevent the corrosion reaction from reaching the steel. This Kit Contains the Following: Takedown/Pivot Pin Detents (2)Bolt Catch Spring (1)Safety Detent Pin (1)Bolt Catch Plunger (1)Bolt Catch Roll Pin (1)Buffer Retention Pin (1)Trigger Pins, 5.56 (2)Safety Detent Spring (1)Spring for Buffer Retainer, 5.56 (1)Springs for Takedown/Pivot Detents, 5.56 (2)Spring for Mag Catch (1)Bolt Catch (1)Safety Selector, 5.56 (1)Magazine Catch Button, 5.56 (1)Magazine Catch, 5.56 (1)Pin for Receiver Pivot, 5.56 (1)Pin for Receiver Takedown, 5.56 (1) RISE Armament Lower Parts Kit 12003