Our 2 knife Corrugated Back Rosette tool holders are designed to produce quality rosettes or plinth blocks on low rpm machines such as drill presses, lathes or (Bridgeport type) milling machines. They are available in three diameters and three shank sizes: 1/2", 3/4", #2 morse taper. A 1/2" or 3/4" shank is included with the tool.