Top surface 14 and bottom surface 16 are flat to about 0.001″ accuracy so as not to degrade {TAIL ~ a spirit levels} leveling {HEAD ~ accuracy} 
Top surface 14 and bottom surface 16 are flat to about 0.001″ accuracy so as not to degrade { TAIL ~ a spirit levels } leveling { HEAD ~ accuracy }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD