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.