Used for indicating & layout.  Hardened steel base surface is ground & polished.  Recessed sides & Vee Groove on the bottom.  Rocker arm adjustment is fine, smooth & rigid.  9-1/2" scriber is hardened & ground.  Groove in front of base allows spindle to be set above or below the base, enabling scriber to act as a depth gauge and a height gage.  Includes a 9" extra spindle.