Wilson combat accu-tac ar flash hider sports a three-pronged external profile and our exclusive external accurizing flutes that improve muzzle harmonics over other blast dispersing brakes.These extensively tested features effectively dissipate flash and minimize muzzle signature but unlike many competitive ar muzzle devices, the accu-tac has no negative impact on accuracy.Hardened 4140 steel, fits standard, gi threaded ar barrels.*note: there are no fire control parts (hammer, trigger, disconnector, springs) included in this kit.Kit includes: bolt catch, bolt catch plunger, bolt catch roll pin, bolt catch spring, magazine catch, magazine catch spring, magazine catch button, pivot pin, takedown pin, 2x pivot/takedown detents, 2x pivot/takedown detent springs, safety detent, safety detent spring, semi-auto safety selector (right hand), trigger guard (aluminum gi), trigger guard roll pin and 2x trigger/hammer pins.Finish: BlackType: Lower Parts KitModel: Lower Parts KitSize: 5.56mmSafety: Lever