The RL556v3 features Polymer80 s proprietary polymer composite, a solid core design, flared magwell, and beefier mil-spec buffer tube housing. The pistol grip area features a unique threadless design specific to Polymer80 rifle lowers. The kit includes: 80% Polymer AR15 Lower Receiver (Mil-spec) Polymer Jig Trigger Hole Drill Guide Drill Bits and End Mill Tactical Superiority is one of the largest suppliers of Lower Parts Kits in the industry. For years we have been an OEM supplier to manufacturers making AR-15's for the commercial market. Kit Includes: (1) Mil-Spec Steel hammer (1) Hammer spring (1) Mil-Spec Steel trigger (1) Trigger spring (2) Hammer/trigger pins (1) Disconnector (1) Disconnector spring (1) Bolt catch (proper mil-spec casted and machined) (1) Bolt catch plunger (1) Bolt catch roll pin (1) Bolt catch spring (1) Buffer retainer (1) Buffer retainer spring (1) Magazine catch (1) Magazine catch button (1) Magazine catch spring (1) A2 pistol grip (1) Pistol grip screw (1) Pistol grip lock washer (1) Standard safety selector (1) Safety selector detent spring (1) Safety selector detent (1) Takedown pin (1) Pivot pin (2) Takedown/pivot pin detents (2) Takedown/pivot pin springs (1) Trigger guard (1) Trigger guard roll pin