The RCBS Hand Case Neck Turner is engineered to achieve consistent case neck thickness by precisely removing brass from the outside of case necks addressing variances in commercially available brass that can cause concentricity and bullet run-out issues.RCBS Hand Case Neck Turner with Quick Change Case HolderMicrometer adjustment dials desired case neck thickness in 0.0005-inch incrementsCaliber specific pilot/mandrels guide the case neck (sold separately)Cutter design allows zeroing to pilot/mandrel for precise setupConfigurable for right- or left-handed useQuick change case holder system for efficiencyEssential for serious handloaders seeking to produce more consistent and accurate ammunition by eliminating case neck thickness variations that affect bullet concentricity and overall cartridge performance.