MFR #: 156757UPC: 661120567578AR-15 Lapping ToolLapping a receiver ensures a perfectly square and true surface for the barrel to mate against, thus enhancing accuracy. Upper receiver/barrel alignment is critical to accuracy. Also, honing the surface can produce optimal positioning of barrel nut so ideal torque can be achieved along with proper gas tube hole alignment.Use with a battery powered or electric drill to square the receiver face on an AR-15Helps align the gas tube through the barrel nut holesHelps align front and rear A2 style sightsFlex Driver Shaft220 Grit Lapping CompoundSteel Construction with a Black Oxide Finish