Sons of Liberty Gun Works' Lower Parts Kit is made from only the highest quality Mil-Spec or better components: The SOLGW Bolt Catch and Safety Selector are a Mil-Spec AISI8620 investment casting per the USGI TDP. (not to be confused with MIM parts in the commercial market). SOLGW's Safety and Takedown Pivot Detents are solid hardened Stainless Steel from KNS Precision Machine. SOLGW Magazine catch and Takedown Pivot Pins are machine from Mil-Spec AISI8620 per the USGI TDP, heat treated and coated per mil spec. SOLGW's Mag Buttons are made from steel per Mil-Spec versus the aluminum found in the majority of commercially available LPKs on the market. Contains: Safety Selector KNS Stainless Selector Detent, Safety Selector Spring, Magazine Catch, Magazine Catch Button, Magazine Catch Spring, Bolt Catch, Bolt Catch Buffer, Bolt Catch Spring, Takedown and Pivot Pins, Takedown/Pivot Pin Springs (2), Takedown/Pivot Pin KNS Stainless Detents (2), Buffer Retainer Pin, Buffer Retainer Spring.