Lapping 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-15
• Helps align the gas tube through the barrel nut holes
• Helps align front and rear A2 style sights
• Flex Driver Shaft
• 220 Grit Lapping Compound
• Steel Construction with a Black Oxide Finish