Shank Type Taper Shank Taper Size NMTB40 Projection Flange to Nose End Inch 3 Milling Machine Arbors are made of top quality one piece forgings Carefully heat treated and surfaces ground with extremely narrow tolerances assure a rigid setup and accurate machining operations All threads are ground Arbors are equipped with assorted width solid spacers and necessary running bushings with standard keyways and threaded arbor nut