Get jobs done easier, faster and with professional results with the Montana Brand Tools Countersink Insert Replacement. Pre-drill and countersink to drive screws flush with the material surface or deep hole counter boring for driving screw heads below the surface. The ultra-sharp cutting flute clears chips efficiently and leaves a clean, smooth hole. This replacement countersink insert has an adjustable drill bit length for desired screw depth and features a flattened shank for a no-slip countersink connection.