This tool will allow you to perfectly align your scope rings prior to lapping. This tool is designed to do both 1″, and 30mm rings with a movable inner rod for ease of alignment. CNC machined of stainless steel to exacting tolerances. Once the points of the tool are brought together, this will indicate if you need to add shims under either the front or rear base. This will eliminate kinked or dinged scopes, as well as give you a perfect alignment of the rings with the action.