3M(TM) CBN Plated Mandrel, Type 1, 220, D=.070 in, R=1/2 in, 1/8 in x 2-1/4 in, 1 per case CBN abrasive grain electroplated on quality steel mandrels, available in 120 & 220 mesh sizes in a wide variety of shapes & sizes, commonly used for ID, jig or contour grinding, hardened steels, superalloys and ferrous metals 40 Rc or harder.