The Wheeler Engineering AR-15 Receiver Lapping Tool allows the builder to true the surface of an AR-15 Upper Receiver to ensure a square surface for the barrel to mate against. This ensures the barrel can be torqued down smoothly and evenly, thus increasing accuracy. Designed to attach to a battery powered or electric drill (not Included), this tool will quickly square the receiver face and allow the barrel nut to be positioned to align the gas tube. FeaturesSteel constructionBlack oxide finishFlex driver shaft220 Grit lapping compound