Our lower parts kits contain all high quality components, manufactured to our exacting standards. Each kit is guaranteed to fit your mil-spec dimension lower receiver. We don't use polymer parts, or MIM parts. These are quality kits at an excellent price. Hammer Trigger Disconnect Bolt catch-.308 Specific Bolt catch detent Selector Selector detent Magazine catch assembly Fire control group pins (2) Takedown pin (DPMS Length) Pivot pin? (DPMS Length) Pivot pin detents (2) Buffer retainer pin Complete spring kit Trigger guard assembly A2 pistol grip assembly*Please note that this kit includes a "standard" magazine catch assembly. The included magazine catch assembly may not be compatible with some lowers that require an extended button.*Takedown/Pivot Pins, Bolt Catch, and Magazine Release Button are not compatible with Aero Precision M5 lower receivers.